Everything that's been shared is useful. I typically will go through the forums, P411, etc., but a few additional things I'll typically do for someone that has no review:
1. http://www.google.com/images - if you mouse over the camera, you can paste the URL of a picture onto it. Not that non-genuine pictures are always an indication of fraud, but it's a start. It sometimes will also lead you to other things to let you know she's legit if she uses a picture she's used someplace else.
2. Google her #. Yep, I used it as a verb, ugh. But just search using the format xxx-xxx-xxxx and you'll be surprised what comes up. I once found a provider that was also selling a washer/dryer on craigslist.
3. http://www.spokeo.com - no, I'm not a stalker and I really don't want to take things outside of where they should be, but it's nice to know that the # you were given (if not a GV, Line2, etc) is that of a 45 year old manpimp. IMHO, Spokeo's monthly $3.95 cost for unlimited searches is worth it. It's also let me help more than one provider realize she needs to abstract herself with GV. Nothing ingratiates you more than someone knowing you're concerned about their privacy. Just advice, wait till after the session to mention it and be tactful and show concern.
Ever piece of the puzzle when doing research gives you the opportunity to detect a "red" flag. The last time I was burned, I failed to be diligent and after the fact went through checks that would have if done prevented me from calling her.
Good luck!