I did a weekend trip this past weekend and it rained nearly the entire time. The piece of equipment which will help you out the most in the rain is a positive attitude. Try to enjoy it if possible, but dont get in a bad mood or it will spread to the rest of the group and ruin the trip. Also make sure that your ground cloth does not stick out beyond your tent or it will funnel water in and turn your shelter into a bathtub.
"cant cheat the mountain pilgrim, mountain got it's own ways"