My personal thoughts on the Pyro c3 skills:
Max Fireball and Firewall, this is a no brainer.
Now you have 15 points to deside what to do with, but there are no cookie cutter way to place them.
Flare sucks, skipp it. This is also a no brainer.
Flame ground is a good skill for when you are low lvl, but bad at high.
I have 4 points in this skill atm, but wish i only had put 1.
Enchant Fire is a nice skill, but there is no need to put more then 5 points into it. If you want to go for 1 (so you have it from time to time), 4 (so it’s maxed when you party a cleric 2) or 5 (100% uptime solo) is up to you.
Fire Pillar is nice, but has a really long CD. It gets bigger at lvl 5 and 10. So pick one of them.
Hell Breath eats up your sp fast and got a low chance for a really nice debuff. Go for 1 or 5.