For myself, the mw and I have to click. That's important.
Just as important, though, are her answers to several questions:
How many births have you attended at? In this area? Can we have a one or
two names/numbers as references? (These are important for me to get a sense of her experience. The more, the better, though I wouldn't automatically rule out a less-experienced mw as long as I liked her other answers and we clicked.)
What is your transfer rate? What is your c/s rate? What is your episiotomy rate? (She should know her rates of these occurances and be willing to share them with you, and to talk about the circumstances behind why they occur.)
What do you do for cord prolapse? Shoulder dystocia? PPH? (Here I'm looking for specific answers. For cord prolapse, I want to hear that she shoves the baby up inside me with one hand and uses the other to call 911. Or similar. For sd, I would like to hear that she tries various positions, including Gaskin's maneuver, and that if all else fails and baby is starting to become distressed she'll counsel transport for a c/s. For PPH, I want to hear what drugs/herbs she carries and how/why she would use each.)
How long do you allow for the placenta to come out on its own? (I want to hear: lots of time. I also want to hear: I don't ever tug on the placenta.)
Have you ever missed the birth of a client? (In my mind, this should be a rare occurance, and there should be a good reason why it happened, and a backup plan in place for if it would ever happen again.)
What are your expectations for clients through pregnancy? In labor? What do you see as your role during pregnancy? In labor? (These let me get a sense of her overall philosophy and if it meshes sufficiently well with mine.)
And you can think of other questions that would be important to you. I had 3.5 pages of questions for the first meeting with my hb mw.

Good thing she was patient, didn't mind answering the questions, and had plenty of time. Those are also good signs in my mind.
hope this helps...
Catherine