The certification process as a general VA would be more worth your time and money. As you begin working with clients, you may find a "natural" niche that you gravitate to.

I just set out to find "at home" work, although I have over 15 years experience in administration, marketing and small business ownership. My first client (through elance.com) was a coach, speaker and author. I am still working with him and have since picked up 3 more clients in the same industry through word of mouth.

Good luck.

Kind regards,
Dawn Beauvais