Here's what I consider my rules. (It may look a little lengthy but it's mostly common sense stuff)…
I've broken it down into:
A: Before the Convention.
B: Before running at the Convention.
C: At the Convention.
D: After the Convention.
BEFORE RUNNING AT THE CONVENTION:
1: Figure out what you want to run and what you will require. This will mean, rules, figures, terrain, scenery, and any of the little "special stuff" that you will need (pencils, dice, tape measures).
2: Figure out the scenario you want to run. # of players, complexity, objectives, time to run it. (Add an hour for set up and take down).
3: PLAY TEST, PLAY TEST, PLAY TEST. (Try running it with different people vs your standard group.) I've found out that after a while, a standard group can fall into a "they're gonna do this" action mentality. New people and new groups will find the weaknesses and problems in the game that the standard group won't.
4: KEEP THE RULES SIMPLE AND FUN. Don't give them a history lesson before and after every turn. They are there for a game, not a lecture.
5: Watch your play-testers. When I say "Watch them", I mean, "Watch what they are doing during the game." See if they show interest in what they are doing, or what the other players are doing. Watch their face to make sure that the most common expression isn't either confusion or boredom.
6: Take notes of everything that the players have problems with. 6 out of 7 of your players have trouble figuring out the morale phase? Go back and see what you can do to make it easier.
BEFORE RUNNING AT THE CONVENTION:
1: Check with the con on your schedule. Make sure they are still okay with it.
2: Inventory your items. Figures, rules, scenery, terrain. The last thing you want to find out is that you drove four hundred miles and accidentally packed your wife's identical bead box instead of your box of artillery and cavalry.
3: Make sure you have everything you need and loaded and packed the day BEFORE you head out to the con. Packing your game stuff the morning you are leaving is a disaster and item #2 above, just waiting to happen. We always oversleep, miss our trip departure times, etc…Be prepared.
4: Give yourself plenty of time to get to the con, and don't rush it. It's a game convention; not the Indy 500. Be prepared for detours, traffic jams, construction issues, that little old lady doing 45 in the 70 lane, that 18 wheeler driver that doesn't know what lane he wants to be in, weather, bathroom breaks, the need for food, and of course the piece of farm equipment driving down the road towards the soy bean field that is 15 miles away and he's doing 30 and you can't pass…
AT THE CONVENTION
1: Show up early, as in EARLY to the convention to make sure that your table is still a "go" and hasn't been A: Moved, B: Claimed for another game, C: Trashed out, or D: That the organizers have dropped the ball on your game.
2: Check your area before you set up. Make sure it's clear of trash and what you have requested. If you need 2 rectangle tables and they give you 1 round one…there's a problem. Being early will make sure this is taken care of.
3:Make sure your scheduled game is still scheduled for when you have it scheduled.
4: Make sure you have the right amount of chairs for players, etc.
5: Don't show up to run a game at the convention p*ssed off about something else. Being made at your neighbor because you caught his dog dropping a steamer in your yard again or getting into a fight with the S.O. and having it eat on you at the con is not a good way to run a game and it will show.
6: Don't be mad at anyone because "You have to run a game at a convention." No one put a gun to your head and forced you to sign up to run one.
7: Make sure you set up your table EXACTLY the way you have accepted the setup in play-tests. To do otherwise is folly.
8: Make sure that the players have ALL the charts, figures, dice, etc that they need and will require.
9: Be on time to run the game. If the game is supposed to be four hours, don't take an hour of that time to still be setting up your terrain. You have just ripped off your players.
10: Remember that you are running the game. It's not a "You vs them" mentality. You are not there to "win".
11: Be open, smile, have fun.
12; Don't tolerate blatant, purposeful rudeness that will spoil everyone else's fun. Don't tolerate cheating.
13: Run the spirit of the game and not the rules. If the rules don't cover something, be ready to improvise. There is no rule system that will cover everything a player can think of.
14: Make sure you can play to completion, or at least a point where it's obvious of victory. Trying to run the battle of Waterloo at battalion level in 3 hours is imbecility. Be realistic.
15: Don't add so many extra players that you can't effectively and smoothly run the game. Adding eight more players to a sixteen player game with one GM is already a disaster waiting to happen.
14: Most of all: "HAVE A FUN GAME"
AFTER THE CONVENTION:
1: Thank your players and let them know how appreciative you were of them.
2: Clean up your table area.
3: Make sure you are properly packed.
4: If possible, get names and emails of anyone interested in gaming with you further. Send them an email 1-2 days later thanking them once again and inviting them for more play (if they are local). You get a lot of new players and friends that way.
5: Let the con organizers know that you are done, your area is clean, and thank them. Also send them a thank you email withing 2-3 days. A simple thank you, goes 100 miles for folks to work cons.
6: Look over what you did and think about if you want to do it again at the next con. If so, start planning asap, and use what you learned to build on.
Hope this helps.