You can never really go wrong casting a heal on the MT - except maybe piss off the MT Warden, if there is one.
I'd rather my heal be overwritten than there not be one on the MT when/if needed. If another druid is faster than I am, then shame on me
If you are not in the MT group or OT group, then yes..your buffs go on you and/or your group. If I'm in the squishy group, I usually 'tank buff' the bard, which they like a lot cause I'm giving them Instinct.
There's probably not 3 Wardens on the raid, so put your thorns on the OT (you can do that out of group), unless there's a fight where you can't have those on.
If there IS 3 Wardens on the raid ..eek.
What you will do on a raid depends on your group setup. If I'm in the OT group with a cleric or shaman, I group heal and single target heal the OT if needed. Once my group is stable - meaning no one needs any health, I've got some HoTs ticking for a little bit - I look across the raid to see if anyone is in need of a heal that I might help with.
I particularly look at the squishier group depending on who their healer is. We almost always have faster casting heals that are just the right amount to bring a choker-wearing caster DPS back to full health, where a cleric or even a fury is doing more than just healing. You can help there.
Triage your heals too. For example: the MT is getting his butt kicked, but the Wizard in G3 has taken a huge hit and is almost dead. Clearly, the MT has the heal priority because if he dies, chances are you will not be able to recover (you might..but generically speaking). DPS is really necessary for a raid's success but you have to keep certain people alive first. That Wizard is used to it (lol), and can be easily and quickly rezzed with not much of a dent in the fight. If a key person is killed (MT, OT, MT healers etc), then it's that much harder to get back on track with the fight. Just use common sense and don't respond to the Necro screaming at you to heal his Lifeburn if your MT or OT are not in good health.
After awhile with the same raid force, you'll begin to know who takes the most damage (choker wearers usually, 2nd to the Tanks), and who is more likely to need healing at what part in any given fight.
Most importantly in TSO is curing. I kind of view my thing as curing since in most cases I'm the faster curer (shaman have some AA that makes them insta cast curers, but they are often refreshing wards when we can step in and do the necessary cure).
Since lack of a cure could mean a death (or even several deaths), even a double effort where I cured and someone else cured isn't a waste.
Your group is assuming you will cure a groupwide elemental dot. If there are back to back groupwide elementals where your group cure is still on cool-down, then there usually is some arrangement about which one you will group cure and which your group will potion cure. Even though you have agreed to a potion cure, start single target curing if a heal isn't needed. There are a lot of dots nowadays that will chew your group up if you don't.
You can't really go wrong by keeping Purity refreshed on the MT, either. You also can't go wrong if you are in a group that you are easily healing with your group heals and you target the MT or OT for single target if they don't have a druid in their group. That kind of gives them the benefit of druid heals (sort of) without losing the dps or power regen that is taking a 2nd or 3rd heal spot in a group.
And after everyone is alive and well, then dps. (This advice is for a new raider, older raiders dps AND keep the groups alive...it takes some practice to know the timing of that).
Bottom line is: they brought you along as a healer, and at your stage of the raiding game probably for your Critical Mitigation buff. Dps when/if you can, but never at the expense of healing.
Saving the raid with a well-placed heal even if it's
not your group..is never dumb
