I thought this might be helpful and interesting given the number of ads on the "Musicians wanted" page that go unanswered.
So anyone want to contribute some useful advice? Am I being a bit Blue Peter-ish by trying to start "how to" guides? Anyway...
People tend to be reluctant to commit to things. It pays to try and get them to agree to just play one gig with you. Assuming the gig goes well, they'll often then stick around.