One useful thing I'd recommend is that you take time to learn the difference between fantasy and reality when it comes to BDSM, because there's a lot of the former in the media, and very little of the later. There are tons of 'sexy' stories and videos and the like, but not a lot of conversation about the important things new subs really need to know.

As the other posters have suggested, learn about the community. Talk to people who're really in it and don't ever assume you 'have' to do something, just because you're a submissive and someone else claims to be a dominant. Never be afraid to ask questions and to speak your mind