I used to do a little babysitting (until I told the parents I was pregnant and they all dropped me ) I charged 15 per hour to care for one child but this is low. In Bris the going rate is/ used to be anywhere from 15 to 25 ish an hour.
What Marcellus said.
Definately ask about the security check, she should have a card of some sort. Maybe do a google search and see if you can find out what it's called and if you can find a picture of one so you know what to look for.
I'd also ask to see a copy of her certificates.

Good luck, I hope she's just what your looking for.

urgh Rodney Rude lol