Good advice all around here. I've been commuting in south Louisiana for several years, and here's a few tips I can add:

Cold water on your face. This triggers the Mammalian Diving Reflex, and causes your body to slow down/cool off very quickly. The water has to be cold, though.

Showering before you ride does help. I bring a towel with me. Wash my whole head in cold water, then towel off in a bathroom stall.

Your clothes (especially synthetics) will hold odor. Best way to get rid of it that I've found is to let them soak in hot water, 15-20 minutes, and then pour 1 cup of vinegar into the washing machine's "bleach" dispenser. Then close the lid, let it wash as normal, and the vinegar will be added during the rinse cycle. For really smelly stuff, you may have to do it a few times, but this really works.