Am in the middle of the Gates to Witch World, which are the first three Witch World books she wrote back in the 60s. Also read The Shadow of Albion and Warlock, which were both really good.
Read Why Girls Are Weird, which I'll recommend if you know who Pamie (of pamie.com fame) is, and maybe even if you don't. It's got its good points and bad points, like any other book, but on the whole I think it's an excellent first novel.
I know there's more, because I returned a mess of library books about two weeks ago, but I can't remember what they were. I'll keep better notes next time. :)