Don't drive if the windshield is so covered with rain that you can't see!
Okay, this one sounds like a no-brainer, but isn't it amazing how many people seem to have been born without brains? It doesn't matter if you know the road so well that you could drive it blindfolded while sound asleep, you still shouldn't drive it while there's enough water on the windshield to provide a home for goldfish. Not being able to see ahead, you don't necessarily know what's there. There could be stopped cars in front of you that you can't see. There may be pedestrians wandering around befuddled in your path. You may not even be driving as straight as you think you are and could be heading straight for a bridge abutment. When visibility gets low, pull off the road as quickly as it's safe to do so. Stop your car. Pop a CD in the dashboard player and listen to soothing music while you wait for things to clear up again. Get out your cell phone and have a conversation with your best friend (but only when you're not driving, remember?). Turn to the person next to you and get to know them better. Wonderful marriages have resulted from less auspicious beginnings.