Keep a node on you at all times treat that rule like its religion. I just recommend it because, for some reason, ripper ammo accumulates so quickly so its an easy way to farm credits. Its not insanely difficult, just required a lot of micromanaging of resources and quick thinking. You technically don't even need to have the ripper tbh, as I did impossible with just the plasma cutter to get those trophies back on the ps3 since those were the last 2 i needed to plat the game. Make sure to carry around a few stasis packs, because you will be using it a lot. Enemy blades, fan blades, etc should be your go to.

Money made that way can be used to purchase plasma cutter ammo & power nodes to upgrade it and your rig.

The ripper will rarely be used, but is only kept because owning it and having it will make ripper ammo drop like crazy, which it drops extremely often and can be sold for a good price. Spend power nodes to upgrade the plasma cutter ASAP, as it will be your primary weapon.

These are the only 2 weapons you will need.

Dead space 1 impossible mode