I've been using a priority system of going to most injured, tank, myself other heals. I've been keeping up, up times on my self buffs like riptide. I keep healing rain and healing stream on cool down. Also earth shield on the active/taunting tank 100% (as close as I can) of the time. Throw out some direct heals on really injured and chain if i see a large dip in hp across the board.
I have no issues with mana, and my activity is always right where it should be (with in a % or two, of the most active. I've even tried using more greater/healing waves more to help reduce the amount of over healing. Which has helped a little.
In my raids we've even had other resto shamans (they've been better geared than I, so i don't expect to come out on top) but i still find a place near the bottom of healing and near the top on over heals.
Is this a product of having too many heals brought to the party, my style of play or something I'm not thinking of that might reflect in my effect I have on the raid? I'm catching grief for my numbers and I'm trying different things and using a bunch of resources to correct the problem but, I'm unable to do so.