The vast majority of the STL Poker Tour games only have one table, so seating is easy.
There is a 5 player minimum for our league.
If there are 7 players, you take the following cards: A, 2, 3, 4, 5, 6 and mix them up, face down, on the table. Have the players draw one card. Ace is the dealer, 2 is small blind, 3 is big blind, etc.
Having more than one table is where it can be complicated, and this is taken from homepokertourney.com:
More than 1 table
If you have more than one table in play, you must decide how you will combine tables as players are eliminated. The easiest method to combine tables is at preset times. For example  you will go from 3 tables down to 2 tables when there are 20 players remaining in the tournament and you will go down from 2 tables to 1 table when there are 10 players remaining.
You will have to seat your players according to the size and shape of your poker tables but this is how you should attempt to seat your players ...
Less than 10 players should play at one table 10 players should play at 1 table. 11 players should play at 1 table or a (table of 6 and a table of 5). 12 players should play at 1 table or a (table of 6 and a table of 6). 13 players should play at 1 table or a (table of 6 and a table of 7). 14 players should play at 1 table or a (table of 7 and a table of 7). 15 players should play at 1 table or a (table of 8 and a table of 7). 16 players should play at 1 table or a (table of 8 and a table of 8). 17 players should play at 1 table or a (table of 9 and a table of 8). 18 players should play at 1 table or a (table of 9 and a table of 9). 19 players should play at 1 table or a (table of 10 and a table of 9). 20 players should play at a (table of 10 and a table of 10). 21 players should play at a (table of 11 and a table of 10) or 3 tables of 7. 22 players should play at a (table of 11 and a table of 11) or (2 tables of 7 and a table of 8). 23 players should play at a (table of 12 and a table of 11) or (2 tables of 8 and a table of 7). 24 players should play at (2 tables of 12) or (3 tables of 8). 25 players should play at (2 tables of 8 and a table of 9).
Assigning seats to players
Prepare a deck of cards consisting of one card for each seat at each table. For example, if you have two tables of 8 players and one table of 9 players, use a deck consisting of the A8 of spades (Table1), the A8 of hearts (Table2), and the A9 of clubs (Table3). When the tourney begins, or when a new table or tables are formed, each player draws a single card. The ace is seated at the button, the 2 is seated at the small blind, the 3 is seated at the big blind, then each player is seated in proper card order around the table. Card suit is used to determine which table a player is seated at  for example, all spades sit at Table1, all hearts sit at Table2, and all clubs sit at Table3.
If you have more than four tables of players, or cannot use a deck of cards to assign seats, use a seat number written on a piece of paper instead. Assign a letter of the alphabet to each table (Table A, Table B, Table C, etc,). Give each player a piece of paper with a seat assignment written on it  A5 or C7 or D1, etc.. Seat A1 is the first seat (and the button) at Table A, Seat A2 is the small blind at Table A, Seat C3 is the big blind at Table D, Seat B4 sits one seat to the left of the big blind at Table B, etc..
Assigning seats to dealers
You will probably have a dealer/player in your game rather than a dedicated dealer. You want the dealer/player to sit in the middle of the table to make it easier to handle the chips in the pot and to make it easier for all players to see the community cards.
If you want three dealers to each sit at three different tables, you first divide your prepared deck of cards into three stacks  one stack of spades, one stack of hearts, and one stack of clubs. Each dealer then randomly draws one card from a different stack and sits in the middle seat at the appropriate table. You then combine all the remaining cards together for the nondealers to draw from. Each player draws a card and then sits, in proper card order, around the dealer. In other words, the dealer chooses his card first and sits in the middle of the table, all the other players then choose their cards and sit in proper order around the dealer.
Assigning a seat to the Tournament Director
The Tournament Director will constantly have to issue rebuys, move players, and perform other duties that will make it necessary to leave his seat and move about the room. As the host of the tournament, I sit in a seat "Reserved for the Tournament Director". I choose a seat that makes it easy to get up from the table to perform various hosting duties  you don't want to be blocked in and force other players to move each time you need to get up from the table. Place a sign or marker on the seat that you want to reserve for the Tournament Director. This special seating will not be any advantage to the Tournament Director since all the other players will be randomly seated around this reserved seat.
Moving Poker Players Between Tables
How to move poker players
If you have more than one table in play, you must balance the number of players sitting at each table. You want to avoid having too many players at one table, while not enough players at another table. For home tournaments consisting of only a couple tables, you should probably balance the tables when the number of players differs by two or more between any tables. If the number of players differs by two or more between any tables, one player must move from the highestpopulated table to the lowestpopulated table. This will ensure a balanced number of players between all tables.
You want to avoid giving a player an advantage or disadvantage when being moved. An advantage would be moving a player, who was just about to pay a big blind, to a table where he is furthest away from paying a big blind. A disadvantage would be moving a player, who has just paid a big blind, to a table where he must once again pay a big blind.
Method 1  Move the player in the same seat
This method of moving players ensures that a moved player is never forced to post two big or small blinds in a row or allowed to deal two hands in a row. In addition, the moved player can simply fill the empty seat vacated by the eliminated player.
When a player is eliminated and a move must be made, the player 'playing a hand' in the same position (seat), relative to the button, at the highestpopulated table must move to the eliminated player's seat. In other words  if the player who busted out was four seats left of the button, move the player from the other table who is sitting four seats left of the button. The move must occur before the next hand is dealt, or the button is advanced, at any table. For the purpose of this rule, a player is 'playing a hand' once all the blinds/antes have been posted and the dealer has begun shuffling (riffles the deck).
Moving occurs at the conclusion of all hands presently being played at all tables. If several players must be moved at the same time, begin with the eliminated player, at the lowest populated table, closest to the left of the button.
When forced to choose between removing a player from two equally populated tables, one card will be dealt (by the lower populated table's dealer) to each of the two tables in question. The lowcarded table will move a player.
Example: There are 8 players at TableA, 8 players at TableB and 7 players at TableC. A player three seats to the left of the button is eliminated from TableC. The TableC dealer deals one card to TableA and one card to TableB. The player presently playing a hand three seats to the left of the button, at the low carded table, must move to the eliminated player's seat at TableC. That player will post the big blind at the new table, just as he would have had to do if he had stayed at his original table.
A moved player will be dealt a hand at the start of the next deal and assume any obligation of the new seat including the posting of a blind or dealing.
Method 2  Move the button player
An alternate method is to move the player at the button from the high table to the seat to the right of the button at the low table.
Method 3  Move the big blind player
An alternate method is to move the player from the high table who will be the big blind on the next hand. This player moves to the empty seat closest (clockwise) to the big blind at the low table.
How to combine tables
If you have more than one table in play, you must decide how you will reduce tables as players are eliminated. The easiest method to combine tables is at preset times as players are eliminated from the tournament. For example  you will go from 3 tables down to 2 tables when there are 20 players remaining in the tournament and you will go down from 2 tables to 1 table when there are 10 players remaining. Adjust these numbers to accommodate the size of your poker tables and whether or not you will have a dedicated dealer occupying a seat at the table. You might have one large poker table that can accommodate 10 players and two smaller tables that can only accommodate 6 players each. You are hosting a tournament of 22 players and they will be seated 10 + 6 + 6 per table. You will go down to two tables when there are 16 players remaining in your tournament and you will go down to one (final) table when there are 10 players remaining.
You must decide how you will seat your players when reducing tables ...

All players redraw for new seats
Use the same method as described on the Seating Players page. Prepare a deck of playing cards containing one card for each seat available at each table. The players each randomly draw one card and sit in that seat. Use different card suits for different tables and use the Ace to designate the button, the 2 for the small blind, the 3 for the big blind, the 4 for the seat to the left of the big blind, etc.. 
Move players from a table that is closing to tables that are remaining open
If you wish to move players to an existing table, rather than completely redrawing for new seats, use a variation of the playing card method described above. Prepare a deck of playing cards containing one card for each seat available at each table. Use different card suits for different tables and use the Ace for the first seat available to the left of the button, the 2 for the second available seat, the 3 for the third available seat, etc.. The players who must move each draw one card from the deck and sit in the appropriate seat.
Example  You might have a 10player and 8player poker table in your basement and a 6player poker table in another room. You have every seat filled (24 players) and you want to close the 6player table in the other room as soon as enough players (6) have been eliminated from the tournament. You randomly seat the 24 players at the three tables. You will move all the remaining players from the 6player table to the other two tables when there are 18 players remaining in the tournament. You will then redraw for seats at the final table when there are 10 players remaining.
You play until there are 18 players remaining  this happens to be 7 players at the 10player table, 7 players at the 8player table, and 4 players at the 6player table. You must move 4 players from the 6player table to the other two tables. Prepare a deck of playing cards containing the ace, 2, and 3 of spades for the 10player table and the ace of hearts for the 8player table. The 4 players each draw one card. The ace of spades sits at the first seat available at the 10player table, the 2 of spades sits in the second seat available, and the 3 of spades sits at the third seat available. The ace of hearts sits at the open seat at the 8player table.
MidTournament seating
If you are reseating all your players at new tables, you might want to attempt to balance out the total number of chips at each table. Although this ensures a bit more fairness, in that all tables will have the same approximate number of chips, it can lead to problems in deciding who sits at what table. Some tournament directors will use a method such as this ...
Largest Stack 1  Table 1 Stack 2  Table 2 Stack 3  Table 3 Stack 4  Table 3 Stack 5  Table 2 Stack 6  Table 1 Stack 7  Table 1 Stack 8  Table 2 Stack 9  Table 3
Seating the final table
If you have more than one table in play, make sure that you announce how you will combine tables and how you will seat the final table. The easiest way to seat your final table is to draw for new seats when you have 10 players remaining in your tournament. All 10 remaining players choose a card and sit in the appropriate seat at the final table.
The number of players at your final table will depend on the size of your poker table, but nine or ten players is probably best. You should probably have a dedicated dealer at your final table, and this dealer will take up one seat at your table. If you have been playing with 10 players at each table and using a dealer/player, you should probably go down to 9 players plus a dedicated dealer for your final table. Finding someone who is willing to deal at the final table should not be a problem since you will have numerous busted out players watching the tournament.
Some players might complain about an unequal number of chips at the final table. Some players might have a great number of chips because they came from tables where the action was wild and there were many rebuys. Other players might have come from more conservative tables, where there were few rebuys and the total number of chips on the table remained low. This is the luck of the draw  all players are randomly seated at the beginning of the tournament.every final table will consist of players with a wide range of chips.
If you are holding a large tournament, you might consider paying out all the players who make the final table. Payout the final nine or ten players and make a big deal out of reaching the final table!
Playing handforhand
You should consider playing handforhand towards the end of your tourney when you are about to seat the final table. For instance, if you have one table of six players and another table of five players and you will seat ten players at the final table ... the next player eliminated will not make the final table. Some players may try to stall (slow down the game) at their own table in the hope that the other table will play more hands and a player from the other table will be eliminated. You must be on guard for the same delaying tactic if you have a large tourney and are paying out, for instance, the top twenty players. If you have three tables of eight players remaining ... some of those players might try to stall in the hopes of having players from other tables go broke first.
For these reasons, you should probably play handforhand at all your tables when you are in a bubble situation. Playing handforhand means that you do not start a new hand at any table until every other table is also ready to start a new hand  every table waits until all the other tables are ready to deal. This will ensure that all tables play the same number of hands.
Shotgun tournament
Another method to move poker players is ... to not move them! A shotgun tournament means that each table will play internally until there is only one player remaining at each table. No players are moved from table to table. Each table winner is then seated to form the final table. The obvious advantage to using a shotgun format is that you don't have to worry about balancing players between tables  no one gets moved until you seat the final table.
One disadvantage of a shotgun tournament is that one table might have a winner after two hours of play while another table takes four hours. Another disadvantage is that you might have the three or four best players all sitting at the same table  only one of those players will advance.
Players might arrive at the final table with differing numbers of chips. Some shotgun tournaments ensure that all players start the final table with equal amounts of chips, while other shotgun tournaments allow each player to keep as many chips as they have earned throughout the tournament.
Shotgun variation
You can use a variation of the shotgun tournament format by playing each table internally until there are only a few players remaining at each table. For instance, if you have a tournament of 27 players  you could seat 3 tables of 9 players and have each table play internally to itself until there are only 3 players remaining at each table. Those 9 players would then form the final table.