Playing well in the rain can challenge even the best golfer. Developing a positive mental attitude to wet weather golf is probably the most important aspect of posting a decent score. In addition to a positive attitude, there are three factors that will influence better rain play -- namely, a good grip, balance, and proper club selection.
In wet weather, it is essential to keep your equipment dry. Carry two towels, one to wipe the clubs and the other to keep your hands dry. Keep a plastic bag cover in your locker. They're cheap and make a huge difference in keeping your grips dry. Assure good footing by cleaning your cleats repeatedly.
When near the green chip to the flag for more consistent results. There's less chance for error with a less-lofted club. Play more aggressively and allow for less roll.
When there is casual water between you and the green, 'hit to the flag' using a lofted pitch and count for the ball to 'plug' near the flag.
Allow for putts to break less on wet greens. Hit the ball harder and make sure you get the ball to the hole.