I tried to play as a healer and I have missed one thing - why I can't heal myself?
Ofc I get some heal from healing others but that's not enough.
Another thing - why can't I buy potions for gold? Creating potions takes too much resources and I can't heal everybody. I hear bad words that I don't help, I don't heal but it's because I don't have enough mana. So healer class is not so attractive.

You need to use your green powder to get a self heal and a % of your own heals.

Self healing via Healing Powder and Healing potions.
Mana healing via Mana Powder and Mana potions.
Potions use their own resource that are good for nothing but potions.
If we had any more self healing we would be so broken we'd basically never die.

And a quick note here, life regen amulet on the Pal is really nice to. It give a huge regen with amu + powder.

Put up green powder and spam right clicks if really needed (you getting more heal with right clicks too). But if not needed stay with holding leftclick. Usually you dont need rightclick that often.

Potions are really important with every class. Get newbie kit with potions and 7 days premium for 1 euro to solve the lack of heal/mana potions. You can also trade nearly all your ressources from energy potions and some empty vials for healpotions.