Yeah, about Cure III procs, it is awesome to heal up your tank and any melee DPS nearby. Proc Cure III uses less MP than straight-up Cure II. To clarify Medica AoE cures outwards of you, the healer. Cure III AoE heals outwards from the target. Cure III covers a smaller area and Medica has a rather large range. I say this because it wasn't the most obvious to me when I started as a CNJ.

Note to self: add a target shout to my Raise macro...

I find having Cleric Stance bound on an extra mouse button is awesome. I have two thumb buttons on my mouse (Razer Deathadder) and one is for Run (Titan did this to me) and the other is Cleric Stance (Transpose as a THM/BLM). Stance dancing becomes so much easier!

Aul is right about Esuna, I cannot emphasize it more. While some debuffs cannot be cleansed, it is important to cleanse the ones that can (like after goal in Titan, or Heavy in fights that require a lot of movements).

In end-game content (ilvl 50+), you don't have to be shy with Medica I/II because usually you are facing a single boss and tanks at this time are more than capable of handling the hate. Medica was rarely needed in low level dungeons and you had to be careful of ripping hate off the tank.

Also, always keep an eye on the Enemy list which will have icons in front of their names. Green, you're good. Yellow, be careful. Red square, you are about to take aggro. Red triangle, you have aggro. POP SHROUD! If need be stop healing, if you can't just keep healing as you go towards your tank. They should by then realize you are squishy if they haven't taken hate back again. DO NOT KITE around the field. If you can, Fluid Aura the enemy to the tank is sometimes suggested.

Also, I love popping Eye for an Eye (ACN 34 skill) after Stoneskin drops on the tank. It helps! Especially on difficult boss fights or speedruns.