Dealing with Elite Mob:
Select your target, buffing yourself, approaching and use Judgment of Life. Use this spell repetitively because it can regain HP during combat. Use Divine Storm and Crusader Strike as possible as you can. Paladin has powerful healing ability compared with other classes.
Use Holy Light or Flash of Light to heal during the combat, you can also use Hand of Protection occasionally, Hand of Protection will temporarily let you immune to Physical damage, but you will not be able to attack your target either. So you can use Bandage or Healing spells at yourself without being interrupted during this time. Divine Shield's cooldown time is not very long. You can use this spell to keep yourself untouched. But remember these two spells will trigger 3 minutes Forbearance effect. You wouldn't be able to use again the spells that can trigger Forbearance effect during this time.
Hammer of Justice is also a frequently used spell, it can stun the target. But long CD time makes this spell can be only used one or two times for each combat.
If your mana is low, use Judgement of Wise instead of Judgement of Light, which can help you regenerating mana. When target's HP reduce to 35% below, you can use Hammer of Wrath to finish him.
When target's HP is very low, he may try to escape. Use Seal of Justice if he do so.
Dealing with Normal Mob:
Use Avenging Wrath to increase your Spell and Attack Power. Because the target doesn't have thick HP, use Divine Storm, Crusader Strike and Judgment of Light. Then use Hammer of Wrath to finish him.