these are mine:

1. Don't use nightvision unless absolutely necessary to progress.

2. Don't invest any skill points unless absolutely necessary to progress.

3. Don't upgrade your plasma rifles unless absolutely necessary to progress.

4. Don't pick Trade Items.

5. Pick up only Craftable Items and use them both to craft and as trading items.

6. Craft only pipebombs, noisemakers and lockpicks. Everything else must be purchased.

7. Never pickup any ammo unless it's in a locked compartments, either in a crate or behind a locked door.

8. Disable the HUD and play without it. Use this mod here by TheJanitor, it lets you toggle the HUD on/off ingame with a hotkey. https://www.nexusmods.com/terminatorresistance/mods/3

I'm playing following these rules and I'm having a blast. It seems that the game is filled up with redundant gameplay systems that only get in the way of a properly intense experience.

Less is more.

Yeah, the overall Terminator athmosphere in this game is fantastic but gameplay is way too easy with all the loot and xray-vision. Hopefully there will be future patches or mods which adresses these things.

edit: after having played the (updated) game a second time with extreme difficulty, I can say thats it's much better now:
-less loot, but still plenty of ammo though
-xray-vision in the settings can be disabled, along other hud elements
-weaker weapons.
-every Terminator poses a threat if they see you, as it should be