Click here to read the first Five Rules to Make you a Better Player.
Rule 6
Think before you play at trick one, especially as declarer.
A great habit for any level player is to take a while to play once dummy is spread. If you always take at least 10 or 15 extra seconds before calling for a card from dummy, you have given the opponents less information than if you simply play quickly when it's an easy hand and you hesitate when the hand is more difficult. Of course, there are some hands that take extra planning and that's perfectly fine. Just try to be as consistent as possible. If you have ever watched some of the top hold 'em poker players on TV, almost all of them are very consistent in their initial action after they see the first two cards. You can certainly learn from these experts even though it's a different game.
Rule 7
Relax and keep your wits when things aren't going well.
It's so easy to lose your cool and concentration when the bridge gods frown upon you, whether for one deal or for a longer period. One of the differences between the top experts and someone who is a good player: the experts can usually put the bad results behind them more easily than the good player. They have learned that some poor results are inevitable and you just have to go on to the next hand. At golf, Tiger Woods was the classic example of someone who was called a "grinder", a term of praise for someone who continues to do his best regardless of what happened recently. If you grind out your best result board after board, you will improve your results and accomplish as much as possible every time you play.
Rule 8
Open 1NT with 15-17 HCP when you have a 5 card major
(assuming that is the range of your opening no trump bid). This makes rebidding much easier most of the time. If you open 1 of a minor and then rebid 1NT after your partner's bid of 1♥️ or 1♠️, it shows about 12-14 HCP with a 5 card major, it is difficult or impossible to show your hand properly in many auctions. There are also many conventions available to show your partner you have a 5 card major after a 1NT opening and a Stayman bid by your partner. Even if you miss an 8 or 9 card fit in a major because you opened 1NT with a 5 card major, you might still achieve an average or better result.
Rule 9
Practice Counting as much as possible
(how many points each player has during the hand and also how many cards they have in each suit). It certainly takes constant practice, but counting definitely pays huge dividends in the long run. The more you do this, the better you become at it, and after a while counting becomes a treasured habit. When you watch a top player who seems to know where every card is located, counting is the reason their play is so impressive. Avoid being lazy and just throwing cards on the table as the hand proceeds. This will help you eliminate those zero percent plays and embarrassing moments when you aren't sure which card to discard at trick 11 or 12 (which can hand declarer an impossible contract or an undeserved overtrick).
Rule 10
Make sure you are an ethical player.
It's MUCH more important than winning. This is expressed perfectly by the profound quote from Grantland Rice, a brilliant early 20th century sportswriter: "When One Great Scorer comes to write against your name, he marks not that you won or lost, but how you played the game."
Click here to read Five More Rules to Make you a Better Player.