L.A.
Make a list of what is important to you and bring it with you. Just go down the list.
Ask where she will be having nap time how long they go down, what food will she be fed, what is the daily routine/schedule. Will she be running errands with kids in her car? If she does, will she let you know beforehand that she will be leaving? Who is her replacement sitter if she is sick? What type of entertainment will they have, tv and movies all day or does she have activities planned? Does she have pets that make you feel uncomfortables? Does she have a seperate room for the children, or is the room they are primarliy in childproofed well and clean?
Does she allow the older children to play outside, for how long? Does she have a pool or play pool that they can play in? See how many children she watches. What kind of punishment does she do, time out, spanking... Does she have a reward chart (for older kids). Does she have older children at home that help, and do you feel comfortable with them as well?
Definately sign a contract. Many in home care providers require sick pay and holiday pay, and are strict about the child's health (b/c they don't want the other children to get sick as well) so see what her requirements are.