I'm quite new to the game so I have only played a few Hazard 4 missions so far, but I seem to struggle quite a bit there. I take too much damage and can't seem to keep up with killing enough bugs.

My question is, once you have unlocked the guns/equipment, there is nothing else to get "stronger" right? I mean apart from some Overclocks perhaps? So is it only a "git gud" thing, or is there any advice how to go about these harder difficulties?

Edit: Thank you all for your great advice! I've played through the Assignment "New Hazard Level: Lethal" and the recent Deep Dive without any real trouble. Rock and Stone!