1. Ask how they search. Make sure your agents is going to use every means possible to find the right home for you. That means using the MLS in addition to their preferred listings.
2. Ask about mortgage connections. It will save you time and headache if your agent can point you toward a good mortgage company.
3. Consider the "vibe" factor. You might be working with this person anywhere from 2 to 12 months, so it certainly helps if you like them...