Never do the Barracks first tactic. It is very cheap and useless if your opponent knows what they're doing. This trick allows you to make 1 grunt, and only 1 grunt. After that, you don't have enough money for a hall. When you attack that 1 grunt, your opponent should be able to kill that grunt with his peons. If that happens, you're dead.

Be courteous to people in the game. Don't be a sore loser if you lose and don't rub a win in the loser's face if you win.

Don't leave a game after you have no hope to win or no men to fight with. Chances are the person/people that beat you want to raze (destroy your buildings) you. It's really annoying when someone surrenders or quits because they've been beaten.

Don't leave a game without telling anyone. It's poor sportsmanship.

When the host says he is starting the game, stop talking in the chat room. Talking right before the game starts can cause you to drop out of the game as it starts.

If someone appears on your drop screen, wait 25 seconds before you drop them.

If you host a game, never under any circumstance, return to chat without everyone's approval.