Well, that depends on which route you want to go. Dark Magician? Sorcerrer of Dark Magic? If you are going for Dark Magician, you might want to wait until the Premium Packs come for the Dark Magic Curtain. A nice and powerful spell for Dark Magician decks.
A friend of mine is running a spellcaster deck with Gravekeepers, Injection Fairy Lily, and Skilled Dark Magician. He has some of the general support for Gravekeepers and Magician's Circle, Mystic Box, and Magicial Dimension for spellcasters. It's a nice idea and when it runs correctly, it has some decent speed to it.
The only problem I have with spellcasters is they tend to be a bit slow at times. So anything to speed them up or slow your opponet down (Swords of Reavling Light, Nightmare Steelcage, etc.) is a good idea.