If you're a warrior cleric, Power Attack is pretty valuable (although useless at level 1).

Divine Spell Power is an oft-overlooked way for a high-Charisma cleric to increase caster level.

Metamagic feats can be good too; I reccomend Smiting Spell at level 3, since the only other good one usable at this level is Extend Spell, and it'd be fairly useless at this level.