1. Be in touch with yourself and what you're comfortable with.
2. COMMUNICATE your comfort levels, desired activities, limits, etc. with whomever you might get involved with BDSM-wise.
3. Know that things change - roles, preferences, etc. - and that this is okay.
4. READ READ READ READ READ. There are forums, educational websites, books, and everything in between that cover BDSM basics - seek them out! But don't read them uncritically. Evaluate what you read and cross-reference.
5. Seek out your local kink community/communities. They often have classes for beginners. As always, be respectful, willing to learn, and firm in your comfort levels/limits.
6. If you're comfortable with porn, watching some BDSM stuff can help you figure out what kinds of activities you might be into. Of course, just like with #4, you want to be a critical evaluator of what you watch - not just a passive watcher.