J.N.
Make sure to get references, ask for a dmv driving record if they will be transporting your child at all, and see if there is an inexpensive way to do a background check online. And make sure to call the references. You're looking for someone who knows how to be around a 5 year old, not just someone wanting a job :)
Your child is also old enough to meet the applicants and give you input on the decision, might not hurt.