Alchemy, Tailoring, and Enchanting are all good caster skills. Alchemy for filling in buff holes. Tailoring for armor to wear/sell. Enchanting is great at higher levels but its such a money sink until ya get the good enchants. Then it rocks with the self-enchanting and charging people for enchants.
Also, in case some people didn't know having two gathering skills first makes big coinage so you don't have to worry about saving up for that mount.