All good advice here - agree with it all.

Some personal handy things I do:

1. Divine Seal. Use it generously, especially before group Regens or MedicaII (sometimes, in SR, with 2 x Melee, you wanna Regen you, your DPS buds, and just Cure the tank. Divine Seal it!
2. Avoid panic by learning that critical second to hit Divine Seal AFTER your cast. Tank about to eat dirt in your SR? Your CureII nearly done? Start pressing DS...by the time the animation for the CureII is done, DS kicks in and you get it on that heal you just did. Eventually you hone that skill so its not a DS button mash but a click (maybe 2) to get that cheat
3. Stoneskin after every mob. I cast it to land just as the final blow (or thereabouts). Then I Cleric Stance, so new mob, first thing I do is AreoII (and while casting that ready AeroI) and basically they hit together. Depending on how Mr Tank is doing....do another enemy, or click off CS and do your thing
4. Benidiction (when you get it). Its not only for the Tank. I Benidict myself sometimes when I have not got time to stop healing others. Even Benidict a DPS now and then (more in BF SR).....and it is very handy for someone newly raised if you aint got time to cure and buff them while still doing what youre doing

Oh. And finally. Don't cry. Don't cry when you've just raised a melee DPS and before you can even cast a single cure on them they run straight back into battle and face-plant again. And don't cry when you use LB3, and everyone is like "F**k yeah! Lets do this!" and then you all wipe. You can be sad. But don't cry. Laugh, like I do