If you plan on leveling solo mostly I can recommend a mix of Protection and Retribution talents like 0/26/25. The following is viewed strictly from a solo leveling/grinding point of view. And I also assume that your gear is not good as well. This might all change as soon as you have better gear available at 60 or if you want to be more efficient in dungeons/groups as well.
Here are my thoughts and alternatives to some talents chosen mentioned:
You don't need Spiritual Focus: Don't get me wrong it is a great talent indeed but it is not required at all for leveling. If you go down the protection route to get to Reckoning you have Improved Hammer of Justice so it will be available more often to heal yourself without being interrupted. You also should take Improved Concentration Aura giving you a 50% chance to avoid pushbacks if Hammer of Justice is on cooldown. And you have 2 bubbles as well you can use to bandage yourself. That is enough in almost every case.
You don't need Consecration: Considering it is working here and does not scale with AP it is just a waste of mana against one or two targets. It does about the damage of a 2H weapon swing over 8 seconds for a bazillion of mana. Don't use it for grinding unless you want to drink constantly.
Parry instead of Imp. Blessing of Might and Imp. Seal of the Crusader: Imp. BoM increases the AP of the BoM by 31 for rank 6. That is like you had 15.5 strength more for 5 talent points. The difference is not noticable and it is just too expensive. And putting 3 points into Imp. SotC talent you deal 21 holy damage more to the target affected by the debuff. It is like you had plus 21 spelldamage. As your damaging spells never benefit from the full amount it is again not worth it.
You should take Parry instead. Most people forget to take it for their leveling specs. But it is a great talent actually. Not only it reduces the melee damage you take by 5% resulting in less mana used for healing, but also after a parry the time to your next swing is reduced by 40% as well (parry haste). So you attack faster. Especially slow weapons benefit from that and you want very slow weapons if you are using Seal of Command. It is a great talent increasing both your damage and defenses.
Imp. Retribution Aura instead of Sanctity Aura: Considering an average mob attack speed of 2 seconds having Improved Retribution Aura would add 900 holy damage done (a little less as you might dodge and the mob might miss) per minute. Later on with gear Sancity Aura will outperform Retribution Aura simply because you can not increase the damage of the RA. But while leveling your gear will most likely be not that good anyway. You also have to keep in mind that you personally will not benefit from RA when you are as damage dealer in a dungeon because you will not be attacked constantly.
Reckoning instead of Vengeance: Your chance for a critical strike will be very low in average leveling gear. You have to keep in mind that Vengeance can't be reapplied while you are affected by it. This means that as soon as Vengeance wears off you hope to get a critical strike again. This often just does not happen when your critical strike chance is low. A better alternative would be going for Reckoning instead. A mob has a 5% chance to crit you which will give you an extra attack that can also cause Seal of Command to go off. If you pull 2 mobs you also benefit from the other mob hacking at you because this will lead to more extra attacks. That way you kill your current target faster as well.
Leveling is not only a matter of damage output but of mana management as well. So don't waste on stuff like Consecration or Judgement spam. You might kill the mob a little faster but you will have to drink more often as well. So you don't benefit from it. Here are a few tips to reduce downtime:
Spirit does not hurt. And it comes for free on many quest rewards or low level items as well. 5 seconds after you last cast a spell your spirit mana regeneration starts. So if you have to cast more than one spell, try to bundle it so you have bigger breaks in between.
Always carry the best bandages for your level with you. When you have to use Divine Shield or Blessing of Protection use a bandage to save some mana.
Recharge your batteries on a mob. If you are running low on mana just save some enough mana to cast Seal of Wisdom, Judgement of Wisdom, Blessing of Wisdom and Seal of the Crusader. Pick a fast weapon with a instant damage proc that is also enchanted with Fiery Weapon. Your normal attack, the weapon damage proc and Fiery Weapon can trigger Justice of Wisdom. That way you have the chance to trigger it 3 times with each attack. Together with Blessing of Wisdom and a little spirit you will be full on mana pretty fast (usually when the mob is dead). This sure depends on your mana pool but for solo grinding your mana pool does not have to be large. The nice thing with this spec is that you basically can use rank 1 Seal of Command and deal about the same damage (only missing out on Judgement of Command).
