Landeril: Also get the spell that prevents Fear. >.> It will help a lot early on.
TrollumThinks: Good point - that also lasts long enough to have on all the time (I think - check the description).
The Cleric spell "Remove Fear" also works to prevent fear, so you can use that instead of using up an offensive Mage spell-slot.
Remove fear is quick to cast, so you can often simply cast it when someone gets affected by fear, especially if the caster with the spell tends to be out of range of AoE spells. In BG2, I have it prepared on a cleric/mage multiclass, and can cast it on those odd occasions it's needed.
Incidentally, there's no way of casting a lower level spell in a higher level slot, is there? Other than contingency, wondrous recall, etc, which only work for specific level slots. There aren't any proper healing spells in the second tier, other than goodberry, and I have liked to fill them with Cure Light Wounds.