I've had quite a few, one was a nightmare, and I actually had to ask the college to remove her, she spent all her time on her mobile ignoring 18 month old she was suppose to be watching on the play equipment in the back garden, child fell off!
When I asked what happened (I had my back to them changing another child) she said dunno.
Repeatedly had to ask her to do anything with the children, really she had no idea and would never have left a child with her.
Another one I had was the exact opposite, brilliant, had all sorts of ideas what to do was great fun and the kids loved her.
Sh is now at 24 a Nursery Manager.
And I had a mixture in between.
You do need ground rules. I have a written set, so that we both no where we are.
And dont be afraid to talk to their turor.