Do some reading ... a lot of reading. Go check out the self-help section of your local B&N. My first time, I obviously didn't have any practical experience, but I had read so much on the subject that I had enough knowledge to make up for it.
Biggest thing to remember your first time is foreplay. If you spend at least 15 or 20 minutes in bed (doing various intimate things which I won't go into), before the clothes come off completely and you have actual intercourse, you'll be better at it than a significant percentage of the guys. The problem with virgins is that they get desperate and rushed.