This is probably YA -- bigger font & space -- but still a good story. Our protagonist, Kim, is keeping herself alive by pulling small cons and housebreaks, and most importantly, pretending to be a boy. She makes a deal to get into a magician's wagon and see if a particular silver bowl is there, and is caught by the magician. It turns out the bowl is part of a heavily magic set that many people are looking for. The magician, Mairelon, takes Kim in, much to the resentment of his man, Hunch, and trains her in magic, culture, and reading. All at the same time, they're risking their lives, tramping through woods, being shot at, and having encounters of the uneasy kind.
This is really a great story and I recommend it. The magicians are part of the Royal College of Wizards, which carries on in Pat & Caroline Stevermer's books, and there is a sequel to this one, Magician's Ward, that I could have sworn I had and the shelves and bookbase say no. So I'll start another book and order the sequel.