Depends a whole lot on what kind of spells you plan to use... when you plan to use some of those a lot, it makes sense to learn feats to enhance them. Other than that, most spells work fine without any feats, too.
Damaging spells (i.e. Blaster):
- Spell Focus
- Greater Spell Focus
- Spell Penetration
- Greater Spell Penetration
- Improved Initiative
- Empower Spell
- Sudden Maximize [Complete Arcane]
Spells with a save, esp. negating save, drawn primarily from one school (i.e. Enchanter, Illusionist):
- Spell Focus
- Greater Spell Focus
Spells with a ranged touch attack (i.e. Ray specialist):
- Point Blank Shot
- Precise Shot
- Empower Spell
Summoning spells:
- Spell Focus (Conjuration)
- Augment Summoning
- Beckon the Frozen [Frostburn]
Buff spells:
- Extend Spell
A feat, that is generally good to have as a wizard:
- Collegiate Wizard [Complete Arcane, Sidebar in the Organizations Section, IIRC]
Bye
Thanee