Generally always go for dmg increase, cooldown reductions and Mana reduction are generally not worth it. Mag defense ignore mostly isn't either.

For skills you want to mainly focus on Ace in the hole, odins spear and aero strafe for damage and clearing with maybe a bit of crazy shot/aero tornado in there.

For utility use non-mod freezing shot, hunters steadiness and stigma shot.

For clearing some leftover enemies that didn't get caught by your clearing skills keep a Guided Arrow/Wind blast on you or replace it with perfect storm for raids.

For bossing just make sure awakening is up, Stigma Shot> Freezing Arrow > Hold Ace in the Hole until the heat death of the universe