(Just in case you've forgotten)
Cards should not be taken out of the board before all players are at the table.
Before you look at your cards count your hand and ensure that you have exactly thirteen cards.
Do greet your opponents at the table and treat them with respect and courtesy.
Do not indulge in post-mortems with your partner directly after a hand is finished. (Save it for after the game.) Not only could a post-mortem undermine partnership confidence, but it may communicate information to players who have not played the hand at other tables.
Do not criticize partner. (Keep it to yourself until after the game. You will have cooled down by then.) And you may also have figured out that you share some of the blame.
Do compliment your opponents for fine bidding or play. (Especially beginners)
Do not gloat! (It is ugly) Be modest.
Do say 'Director Please' in a pleasant tone. Keep your hand up so that the Director can quickly determine who called.
Do support your partner at all times. She/he is the only player in the room that is on your side!