WHM returned player help

[Renalt]

You might try Duty Support. It lets you run with three NPCs (for example, Thancred, Estinian, and Y'shtola) instead of real people.
It's a little slower than running with real people, but not bad, and the NPCs don't mind suffering.

I use it sometimes to level my DPS classes; it's faster than waiting for Duty Finder and the NPCs all know the mechanics well enough.

Sidenote: I started this game as Conj/WHM, and took WHM to 90, but I prefer Sage now.

I don't recommend trying to learn healer doing it with Duty Support just cause they tend to single target and single pull. You won't need to heal at all. Probably won't even need to toss a regen. You'll just be Stone/Glare/Holy/ spamming the entire time.

Just do things with a group and let them know you are learning. Best way to learn is "trial by fire". You will make mistakes...and that's fine but going easy is not doing you favors.

[Silverbane]

I don't recommend trying to learn healer doing it with Duty Support just cause they tend to single target and single pull. You won't need to heal at all. Probably won't even need to toss a regen. You'll just be Stone/Glare/Holy/ spamming the entire time.

Perhaps, but IMHO it's still better than trying to practice being a healer on a striking dummy (is that even possible?)
And you get EXP and loot for your trouble.

[Rein_eon_Osborne]

Assuming Duty Support functions similarly like Trust NPCs, you can also pull more for your tank to raise the bar on your whim. Mind you that you’ll get slapped a few times (usually..) but normally it’s not enough to kill you before your tank manage to rip the aggro off you.