I've had a lot of success with this team build in the early game:
Shield with pistol and lots of flashbangs
2 Machine Gunners
2 Snipers
3 Riflemen with grenades.
Hunter Scout for near constant supression. I generally don't shoot the aliens directly but aim nearby
Snipers are the main killers in the early game for me. Their damage in this mod is insanely high, though they get an aim penalty it seems if they move before their shot, so there's some positioning finesse to be had.
Xenomorphs and Reapers are still a pain but I just don't play games of luck with them. I'll have my snipers take shots at them (they can usually down them in one hit) and if that doesn't work I toss grenades on top of them and be done with it. Once I get flamethrowers, I generally have a couple high strength Riflemen carry a flamethrower in their backpack to deal with the reapers and xenos.