I’m not sure why you are having problems. Early on I took the upgrades that increase my health, gave me more healing from medpacks (huge increase in first level) and increase from recycling, then increased weapons damage. It’s also pretty easy to hide from many enemies. There are vents all over the place which are great to hide in, and they will eventually lose interest. Mimics, the most common enemy are easy to gloo and wrench. You can also gloo phantoms, then run and hide. You don’t have to kill everything and shouldn’t try until you get stronger. It’s also easier to kill them if you duck in a room, then hit/shoot them from the side as they come door. Early on you have to pick your battles, later on you can pretty much take on anything. Also use turrets to your advantage, a couple of them will kill mimics, and distract phantoms while you attack.