Knightster637, pay attention to Fin_676' post...being in Scotland where it rains "--sometimes with out end" means not sitting in a puddle of water, so I make sure whatever rain pants I wear, that the inner seams are sealed...dont' ask me how I know...that blue comin' out the eyes are not tears, but overflow after a long rain...when you have had it up to there!:bigsmiley15:
+2 on this info and the post by Fin67.
If you have/use a rain suit, it is a good idea to coat it with waterproof spray after a significant use of the suit. Especially at the seams. When you straddle the bike you tend strain the crotch seams in pants and that opens holes for the water.
Water carries a good bit of grit and grime from the road and it really works its way in, so a good gleaning afterword is a must.
I also keep a several microfiber cloths in a dry, easy to reach spot. Mind the seal around your neck as water will work it's way in there, especially from side spray from a passing truck.
Watch for tire ruts that collect water and make sure you tread is good on the tires. Make sure you know how to quickly put on your hazard lights, with out looking.
Learn to relax. The first time I rode in the rain I was very tense. This will fatigue you quickly.
Depending on your gear, the first time some things get wet, they will release dye. You may end up with stained skin and clothes.
Know how to take apart your helmet to dry the padding or it will smell bad quickly and get uncomfortable.