Her second and third novels, both set in the Hainish milieu. Both are minor in relation to the works about to come, but I think Planet of Exile (assuming I'm remembering it correctly) is excellent and the other is okay. Her next seven books are the ones which "made" her. I don't like the Earthsea books but her next three other novels and her first collection (especially) were landmarks (or, in the case of The Lathe of Heaven, probably should have been).