This is the most important advice - running out of MP is not a concern for SCH, even if you're burning through it with DPS spells. WHM, on the other hand, don't have the benefit of the same MP pool.
It should also be noted, as others have said, that timing cures is very important. In second coil, WHM can't really afford to wait until damage lands to begin to cast a heal (whereas SCH has the Lustrate EZ-mode reaction heal button).
Waiting until Spit lands before casting aoe heal? Tank gets Bloody Caress and dies before your following Cure II lands.
Other similar instances where the WHM is primarily responsible for landing heals immediately following damage:Notice a pattern? The WHM is responsible for bringing the party up to survivable HP after almost every instance of large damage. When milliseconds count, your big heal is only 2 seconds away. You can't afford to be reactive.
- Swarm explosion
- Superslug hits
- Rotten stench damage
- After Deathdancer, Prosector cleaves.
- Dreadnought roto-swipes and auto-attacks
- Mines
- Allagan field explosion
- Defensive reaction explosion
- Avatar conal
- 1st of 2 Meteor streams
- Raven dive, Dalamut dive
- Ravensbeak
- Raven's Ascent
Other general observations:
SCH Cleric stance - Many parties also delegate their WHM to the filler-healing of Cure I spam while the SCH is in Cleric Stance. This adds a further level of complication, since Cure I spam is often insufficient in keeping the tank and party topped off. There are very few instances where a SCH isn't typically in Cleric Stance (during super add phases, which usually last less than 30 seconds, and during Bahamut's Claw).
Regen global cooldown - Your most useful ability, Regen, is also a death sentence if you use it at the wrong time or just get plain unlucky. SCH can sit pretty getting locked out by Bio and Aero, because they can always fall back on Lustrate as their instant heal. WHM doesn't have that luxury. The less Regens you cast, the more likely you'll run out of MP. The more Regens you cast, the more open you are to bad moments and bad luck.
Stoneskin - The instances where you have to cast this are almost always instances where you want the target to also be topped off. SCH have the luxury of a built-in heal to their proactive shielding (Adlo's 300 potency heal), Embrace (which is usually macroed together with Adlo for a total of 600 heal with every Adlo shield), and Lustrates for good measure (if you're really that lazy of a SCH). In contrast, the only heal that will tick during a Stoneskin cast for WHM is Regen, which has its limitations as noted above. So, this a 3-second cast during which all you can do is pray, or, probably, be cursing yourself because you couldn't keep the target topped off before starting Stoneskin. If you're ever in the situation where you trade off topping off the target and not casting Stoneskin, you're gonna have a bad time (Ravensbeak says hello).