Yea practice makes perfect, but what seems to work for me is the idea that if you're healing, your partners should never be below 50% PERIOD for more than a second. If I accomplish that in a dungeon/raid, then i've succeeded in being awesome.
Mana conserving is the biggest issue wit me, so gear wise I load on spirit and intel, spellpower comes with the intel, so really i put spirit on priority, helps me keep up with the damn tanks that want to speed run %@!#.
With spells heal is your best friend, yea the cast time and power is lame, but it's the cheapest spell and if your people are good, you don't have to reallly use the bigger spells much. I only use the big ones when %@!# gets hot and more than one person is losing hp.
Timing or time in general is another focus, utitlize all the spells that can buy you time for bigger or longer casting heals, if anyone even BEGINS to lose hp I'll pop a shield on them, renew, or prayer of mending (you'll get that in later levels) or any instant heal i have at the time. It just buys me some time to get a heal in before they kick the bucket.
At 34 it's a *!@!* because you dont' have prayer of healing yet, least i don't think so...forgot when i got it. So group healing becomes a pain, but like Amelia said lots of practice will get you better.
So far only about 6 times has someone died in a dungeon run because I failed....ever....bg's that's another story, but even then if someone was near me chances are they didn't die til i died. So I kinda pride myself with at least that, gonna try n keep that number below 10 from now and on to lvl 85 :).
Oh yea as far as aggro is concerned....use fade man, you have like a 97% chance they'll revert back to the tank when you use it.
Good luck buddy.
Edited by Ufu on 12/6/2010 10:08 PM PST