Here are some playstyle fixes to solve your problems after you have all your gear & hotkeys down pat.

1) If you plan on using skills like ressurect alot, keep your mana bar in check and use that mana charge for yourself. You need to have enough mana to heal your party member after ressurecting them, and ressurect is a mana heavy skill. You have much better things to do than mana infusion, so don't be stingy on that mana charge unless you plan on using it to cap your tanks mana or need to provide mana for mechanical situations like dps shields since its also a long cooldown.

Try not to overheal when everyone is full health, use that time to do other stuff and keep your camera on the boss + your party members, you might animation lock yourself into a boss mechanic that you cant dodge in time if you keep overhealing.

2) Focus heal is your low cooldown, spammable heal that tops everyone up when everything is fine. I use it so much that it's binded to my left click.

3) Bind the keys around your WASD keys to extended upper and extended lower shortcuts & just re-allocate the keys you overlap to your liking. Once you have a good setup, get used to it.

4) When someone takes aggro from something & they haven't hit it, your heal will generate enough aggro for it to target you, so if you can, use AOE heals in those situations for minimal aggro.

AOE heals generate less aggro but have a higher cooldown (sometimes shared) so figure out which skills have a shared cooldown & learn how much each aoe heals, how big the aoe is, distance needed to cast the heal / aim, and use the aoe heal when it is safe to do so, without putting yourself in a dangerous situation to aoe heal someone.

People will run at you when they are low hp, and may die, then pass aggro to you, if they run behind you, you won't be able to watch the boss/mobs and heal them at the same time, so ask them to try not to walk behind you, and move backwards while aiming at them so you can see the boss/mobs while healing & be ready to dodge any mechanics.

You will sometimes need to kite with aggro, use lullaby to sleep 1 mob to stall aggro (I bind lullaby to middle mouse button), use prayer of peace when you have too much aggro if you have it glyphed in the future, rely on your party to take the aggro back off you depending on who your tank is.

Extreme situations, you could use eclipse potions but I don't think you will ever need them as a healer and they are probably ineffective for the type of aggro you will be getting.

PVE wise for crystals all you want are mana regen & combat movementspeed reds & fine hardy / anarchic blues depending on your level.