yeah I found medic class is good to start with but I think Defensive is where it's at because on the (i think) second tier there is a skill that lowers the CD of your turret ability which is super important as a distracting ability to the NPCs

On that note my current standing is medic tree all the way down then followingup on defensive since i play mostly online.

My main gun class is mostly the SMG and pistol because up close the pistol rips guys up with rapid headshots (repeater)

I'm only about lvl11 but I spec'd into the extra bullet damage and something else, can't remember. I tried to stick to my thought process on talent builds in wow... damage comes first

Sniper level 27