I have an aupair handbook - it sets out a detailed timetable for school hols and for term time (from what time she has to be up, when she does housework, what time she needs to start walking the children to school etc), house rules, cleaning roster, telephone numbers (me, dh, school, emergencies), useful local info (GPs, bank, supermarkets, language schools, library, cinemas, chemists, website/facebook groups to make friends), tourist info, maps of the area, London A-Z.
I update this info every time I change aupairs. My house rules get longer!
When the aupair arrives, I set her up with an Oyster card (London), register her at GPs, make sure she opens a bank account, show her around the area, introduce her to other aupairs (this info I would have obtained from the outgoing aupair), introduce her to other families on the street, help her to register for language classes or courses, ask her what food she likes or wants to include on our shopping list.