Could you give us some more information about your paladin? Some general advice:
1. Make sure you're using a 1H and shield if you're struggling
2, don't bother memorizing healing spells as a paladin, it's not worth it. Stick to potions
3, make you cast Aid, Bless, Bull's Strength, and Greater Magic Weapon on yourself.
4, as a more advanced tactic, use Prayer and Divine Favor to add a shorter duration bonus
5, going on the above, here's the spells you probably want memorized (assuming you have no metamagic feat (Extend ideally))
Paladin 1: 1 Bless, rest Divine Favor
Paladin 2: 1 Aid, 1 Bull's Strength, 1 Aura of Glory, 1 Eagle's Splendor
Paladin 3: 1 Greater Magic Weapon, rest Prayers
Paladin 4: 1 Death Ward, 1 Freedom of Movement, rest Holy Swords