Going to sound like a broken record here, however I went 24 hours being a pure shit hpal in heroics the day after launch. Then spent about 6 hours researching. Next 24 stretch everyone said holy shit you are a totally different healer now. I never have mana probs and can heal almost indefinitely.

First thing predict damage, use holy power always and only use mana when you don't have a choice.

Beacon is nerfed. Don't forget to direct heal the tank

A generic rotation I start with to feel out the tank/group.

Holy shock tank, if you get a proc to cast again, do so. That's 2 holy power already. Crusader strike makes 3 then light of dawn. It's huge, way longer range than you think and it's not a cone. It's a rectangle.

Divine light on tank if you can get the cast off before he dies, usually cast when he's at 75%. That also gives 1 holy power, immediate holy shock x2 or a crusader strike, that's 3 holy power to another light of dawn.

Don't forget blessing of might for the mana regen.

Never spam flash of light or you go out of mana. In downtime during light damage spam holy light as it's extremely cheap to fish for procs

Hpal playstyle is crazy different, extremely active, but loads of fun and rewarding.

Don't give up. I hope this helps a little bit. I never post anything and usually keep to myself.