I did git gud. It's actually become way too easy. I can kill most enemies in 1-2 fist weapon hits but I still die just because there's absolutely nothing you can do when you enter a new area or room and they get the initiative.
You seriously can't see the contradiction in this sentence?
I mean in general it's too easy, with the exception of the moments mentioned. I support the idea that enemies should be able to do as much damage as me, that's where most games fail, but it would be nice if I could actually survive 1 enemy turn with the heaviest armor. That would probably fix the initiative problem.
Epeli did a great summary above, explaing about stealth and initiative.
As I see it, stealth is extremely useful. However, you are squishy in a stealth outfit, so you need to be able to prepare and ambush well.
If you have no stealth, you got basically two options if you want to live: very good initiative, or very hard skin.
If you have excellent initiative, you will go first, and do major damage and/or battlefield control.
If neither stealth or good initiative, you got to have great constitution, good HPs, good armor. Else, you will die. A telekinetic punch or electro-zap, X-bow critical, stealth knife carving of intestines, you have got to be able to take it.
In any case you got to make good use of terrain, especially without stealth. Use ventilation ducts, doorways, corners. Throw a grenade even without any skill, to lure enemies by the noise. Listen to sounds, set traps as a precaution for fallback if you can, and not be afraid to burn through expensive items. You need them to survive.