Now that I have Holy, I don't want to cast it.

[_slowpoke_]

dropping your MP to even sub 40% isn't a detriment to your role if you play properly (which comes with experience).

This so much. You'll have so many tools on level 60 that allow you to keep the group alive (not topped off, but alive) even if you're at literally zero MP. Learn to use Benediction very liberally, once you get it. It's free, it's instant, it saves you a ton of MP - MP you could spend on spamming Holy instead. Don't let it rot in a corner of your hotbar for that "OH SHIT" moment that comes once in a blue moon. Freecure procs are also amazing, use them and fish for them if you're low on MP. All of the Heavensward abilities that aren't purely offensive are also free, instant, and should be on CD most of the time, keeping your MP up for more Holy spam.

But, as Ghishlain also pointed out, much of this comes from experience. You'll gradually learn to gauge the amount of incoming damage on your party in the next X GCDs, how long you can leave your tank alone without healing them, whether or not someone needs a heal right now or whether they can wait until you've (re)applied your DoTs or gotten off another Holy or two. Most importantly: don't be afraid of failure, and take reasonable risks every now and then. You won't learn anything by always perfectly playing it safe.

[Gemina]

So many great tips! Thank you guys. I am actually excited to use it now, but I am still lacking abilities you guys have mentioned that really help. I am still a young WHM in training, but I will get there. With 50 around the corner I really want to be worthy of my healer's robe. Bring on Aurum Vale. I'm ready to whack some weeds!

[VanilleFang]

So many great tips! Thank you guys. I am actually excited to use it now, but I am still lacking abilities you guys have mentioned that really help. I am still a young WHM in training, but I will get there. With 50 around the corner I really want to be worthy of my healer's robe. Bring on Aurum Vale. I'm ready to whack some weeds!

That's a good attitude to have! It takes a bit of practice but I'm sure you'll do fine.