Games: Bid the safest game. At matchpoints, you may get a markedly better score for playing in notrump instead of a major, or in a major instead of a minor. IMP scoring, however, neutralizes the differences between these contracts. Your best strategy is to choose your best (longest) trump fit and bid the game that's most likely to make -- even if it's 5C instead of 3NT.
Part scores: Look for the safest part score. Don't worry about searching for a few extra points by playing in notrump instead of a minor.
Overcalls: Matchpoint players often make light overcalls, but it pays to beef up your overcalls at IMPs. If you're vulnerable -- or if your overcall is at the 2-level -- you should promise a strong suit and the playing strength of a full opening bid.
Competing and balancing: Don't be too bold. Unless you have a good suit and good hand, let the opponents play in their low-level contracts, especially if you're vulnerable. Trump length is more important than overall strength, so don't let the opponents push you to the 3-level unless you have a 9-card trump fit.
Doubles: There's little to gain -- and much to lose -- by making a penalty double of a close contract, especially a part score. Don't make a penalty double unless you're reasonably sure the contract is going down at least two tricks. If the opponents sacrifice against your game and you are in doubt about whether to bid higher, double and take your sure plus score.
Sacrifices: If you want to take a non-vulnerable
sacrifice over your opponent's vulnerable game, you should be
reasonably sure that you won't go down more than two tricks. If
you're vulnerable, you should be virtually certain that you won't
go down more than one trick. Anything more is "too close
for comfort" at IMP play, and won't gain you many IMPs. When
in doubt, let the opponents play the contract and hope you can
Overtricks: When you're declarer, don't risk your contract trying to make an overtrick. Always choose the safest line of play to make your contract, even if it might cost you an overtrick or two.
Opening leads: Be cautious about trying for a swing with an unusual opening lead. In the long run, it's usually best to make your "normal" lead -- the same one you think your opponent will make when the board is played at your team-mates' table. Save your brilliant defensive plays for later in the hand, when you have more information.
Defense: Be optimistic and fairly aggressive when defending the opponents' contracts. If there's a layout of the cards that will result in a set, choose your leads and plays to cater to that possibility, even if it means you may give up an overtrick if you're wrong.