What do i do next?!

I currently have a full-time job but I want to become an aupair! I have signed up to a few aupair websites and have been in contact with quite a few families that seem interested/I am interested in.
However! I have never done this before and therefore don't really know how it works?!
Once I have contacted/established interest in a family, what do I do next? What do I need? Visa.. insurance.. a contract with the family.. eu driving licence/insurance? etc.. (The important parts)
Also.. I was curious as to how much money au pairs were taking with them on average for their daily needs etc. ?

Id be grateful for any help!