Post by Seahawks
Its always rough at first, but not impossible. People saying you need 1800 SP to run a heroic as a healer are the same ones who think you should have full T7-7.5 to get into their Naxx groups. Its overkill and unnecessary.
As a holy priest myuself, I had jumped right into heroics the moment I dinged 80 and this was back when people had been doing heroics for maybe a few days because no one was 80 yet. Your gear is fine to start with but if you do not feel comfortable with your ability to keep someone alive then just run the easier heroics first. They're generally ranked in the same order as if you were leveling 70-80. You also have the benefit of many, many (depending on server!) cheap BoEs from Nax 10, 25, EoE, Ulduar that you can purchase off the AH for an immediate boost to your stats.
At first, sometimes you'll have an easy time of it, sometimes it'll be rough. Its going to depend on your group and your tank. Don't feel like a death is your fault, I realize the healers get blamed a lot but more often than not the death is the result of a stupid move from a fellow group member.
Your armory is in fact showing your shadow spec and seems to crash when I try to click over to your holy, so I can't offer any tips on spec adjusting or your gear (you said you'd probably be wearing your shadow gear on the armory, thats what it looks like atm)
As for the use of GS, I only use it if I have a lot of healing to do. i.e. the group just took a lot of damage from an AE, I'll pop it on the tank then hit a PoH and renew the tank as well. That way he's covered with extra healing effects from the PoH while everyone else is getting topped off. It's not something you're going to use a lot or even often. Its a situational "uh oh!" button.
You know your spec, if you'd like you can check my profile and see my priest's spec if you want to compare notes. I've never had any problem healing with my current set up, even while I was getting myself geared up.
Edit: I was finally able to click over to your Holy Spec. Your first major improvement you need is Glyphs! You only have two on your holy spec! tsk tsk. I personally run with:
Glyph of Flash Heal -
Glyph of Prayer of Healing -
Glyph of Renew - then the minor stuff, lowered fort cost, no regeant levitate and fading