I commute, rain or shine.

Fenders help a lot. They keep spray out of your face and off your back. They keep the bike cleaner.
Get a rain jacket, the brightest florescent color you can find.
Light up, front and back.
Koolstop salmon brake pads really do work better than most in the rain, still plan on longer braking distances.
Stay off painted lines when possible.

Enjoy it, here in SoCal it's rare enough to feel like an event.