First check your bank to see if you have any cash on hand. If so, hit the bazaar and check for upgrades. You'll probably find better gear than your current stuff fairly cheap.
Also, if you are getting all expansions right off the bat (Buy titanium edition for $20, and then you just need PoR), I would look into Monster missions to get easy quick upgrades. Not great stuff, but free, and easy to get. If you click on the EQforums link on the left, there is a discussion thread with a list of monster missions and what they drop. However, note that you play a monster in these, not your regular character, so expect to have to learn a whole new subgame to do them. Might be best to play the real EQ for a month or so first.
Probably the easiest one to get right now, would be the Dain1 mission in icewell keep. One of the possible rewards is a fairly nice shield, that is cleric usable. However, the reward you receive is level based, and you don't get the best one unless you are level 61 or higher.
Ignore AAs for now. Levels are much more important. Your power will increase more by getting the PoP and OOW spells than it will by AAs.
Levelling in DoD spell missions is a pretty good plan. There are three levels of the 69 and 70 series spell missions. What you will want is the average level 65 missions, so plan your groups around that. Make sure the tank is the highest level in the group, and you'll be fine. The rewards are 100hp/mana+ items, and the nice part about them is that they are what is called cursor loot, which means each group member gets one. There is also a single "chest loot" that is similar quality, but tradable. They sell for quite a bit in the bazaar, and make a good lure to entice that high level tank to help you out.
Once you are level 68 or higher, head over to arcstone, and look for a "spirit mark" group. The rewards are fairly nice armor, about elemental planes quality, like this piece:
https://everquest.allakhazam.com/db/item.html?item=48079 Note that the highest level DoN merchant armor is required level 70, and is not as good as this. With monster mission gear, and bazaar gear, you should be ok in arcstone (since you're a cleric, not a tank).
Once you are 70, with the arcstone armor, go back through the DoD spell missions, on "Normal difficulty". That will yield drops in the 130-170ish hp/mana range. Also look into the other Arcstone quest at that time, for a real nice cloak, and check into the relic quests for rings/earrings.
During this time, also accept groups in OOW and DoD non-instanced zones. This is where you will get the runes you need for your 66-70 spells.