On my mixed groups (warrior, hunter, warlock, priest and 1 of any class), I use priest to heal and others to help lower damage done to tank. Warlock uses curse of recklessness for weak mobs (no running), or curse of weakness for stronger ones. The less the healer has to heal, the more he can help DPS. My hunter uses scorpid sting to lower damage done (misses 5%). Warrior uses demo shout and thunder clap. Most parts add up so I don't have to heal a lot. My priest uses a bubble at same time warrior charges or range pulls. It happens like .1 sec before mobs aggro, so only tank gets aggro and then doesn't need heal for a while. I have talent that lowers rage loss and I try to end fight with 70%+ rage. That way I can use any move I want and don't have to worry about getting rage (or missing rage from bubble).

On my shammies (only 34), I use 4 healing totems and 1 mana. Very rarely do I need to heal. I use a scatter/stagger lesser heal, 2 at a time. Example:
/castsequence [target=focus-target-target] reset=combat Lesser Healing Wave, , , Lesser Healing Wave (alt 1 and 3)
/castsequence [target=focus-target-target] reset=combat , Lesser Healing Wave, , , Lesser Healing Wave (alt 2 and 4)
It works really well. There isn't any tank, but whoever has aggro gets healed and it ends up sharing damage across 3-4 people, so people don't need heals a lot.

On my hunters (39), I use Gift of the Naaru. For BG's, I use 2 waves of it to only heal my main. Every rogue in the BG thinks he wants to show off by killing my main and disabling me, so I put 3 GotN on my main on one push and then 2 more on second push. I also use potions. In instances, I use pets to tank and hunters to off tank. Mostly send in pets, and if they get hurt a lot, I multishot and pull a couple mobs to me and into traps. If I don't want them on me anymore, I use pets to get them off me (taunt) or feign. All my pets have growl on, so they share the damage pretty equally.

My main goal is to lower damage on mixed group or spread out damage on my same groups. Not sure if that helped.