I am a Switch, predominantly sensual Submissive. I've been in the D/s lifestyle for almost 15 years.
Most of what's been said here is wonderful advice. The one thing I will say is that when you are first setting out to explore the BDSM lifestyle, and your nature as a submissive, and his as a Dominant, there will be lots of moments when you "chicken out". Make sure you have open, honest communication, make sure you have a safeword, make sure you both understand your limits.
Two places to visit:
First:
Castle Realm .... This is an AMAZING resource site for all Dominants and submissives and anyone interested in learning more about BDSM.
The second site is perhaps the most important:
BDSM Play Partner Checklist .... Anyone who is active in BDSM, especially if you do not have a regular partner or are just starting out with your partner should have a BDSM Submissive's checklist done. Your Dom should do one, too. This one is one of the most detailed I've ever seen. I've had a version of a checklist filled out for almost the entire 15 years... Even when I wasn't active in the lifestyle, I still occasionally took it out and updated it when I tried something new, even in a vanilla context.
It is a rich, and rewarding lifestyle for those who are possessed of the nature and inclination to life it. Good luck!!
Bryn