Ok, I am not a Mistress but wanted to give my thoughts.
When I first got started (same as you, I was asked to Top but found it wasn't for me) I found this site...Which as been the best place for me to learn. I also found a mentor that helped me further my submissiveness and a lot of my self discovery.
Read the threads in General Talk, Knowledge Base, and My BDSM Life...you will learn a lot.
subwife