Fetlife is a good venue and some of the people in the alt lifestyle scene are some of the nicest people you'll ever meet who will bend over backwards for others. And then, like in life, some aren't. Someone mentioned munches...those are great places to meet others in a "vanilla" environment. Most urban areas have a group on fetlife and some even have a group just for dom(me)s and subs. In fact, where I'm from, there is even a monthly meeting for submissives.
Also, like others have said, the alt lifestyle community is VERY TG friendly.
Just DON'T meet someone in private for the first time and if someone wants to do something you feel uncomfortable with, you have a right (even as a submissive) to say "no." A REAL Dom(me) will respect your boundaries.
Jane