Different skills concentrate on for dual gunner are different. As a DG, you need to check your tier skills first. Skip corrosive. Ivy is nice, but only for 1 level(aika online gold). If you're getting a wind pran and an evasion basis, then use it as an evasion selfbuff because the 1 level of quicksilver is good for the movespeed, or max it.
Hot Shot is very nice early game for soloing. That's the only time it's ever nice, actually. If you're in over your head 1 level of stealth allows you to deaggro mobs. Black Rose is very nice for your character. So you can maxing it. Foxglove's pretty good for PVE. You can put extra points into it in Aika.
Would be better if our range was longer to Max maelstrom. Tiger Eye's nice. Not essential but nice. Sirrocco's meh. 1 level is nice if you're going evasion heavy. More than that is a waste. By the way Hemlock does nothing in PVE.
And you need to make the crossfire max. 1 level of Concussive to control a double pull. Belladonna is crap for PVE, healing mobs kill themselves quickly with it but you get no quest credit for the kill. Flashbang does nothing in PVE except a bit of aoe damage. 1 level of reload. Heartbreaker level 1 is great for PVE. More levels than 1 is mostly a PVP thing but if you have extra points go for it.