Tiffany rules!!!
The third of Tiffany Achings adventures with the Wee Free Men - hard to tell what age would like it, but it is written for Terry's daughters, so they're the best test, I suppose. All three of these show the lessons of a young witch in training, and show what a witch really is, and what they are supposed to be, very different from what popular myth portrays. Can also recommend the first two books in the series, "the Wee Free Men" and "Hat full of Sky"