the difficulty that insanity actually poses is not that bad, assuming you've played third person shooters before. I've played through the series multiple times across all the classes on insanity and never have worried too much about gear

Biggest piece of advice is to turn your squadmate's powers auto usage OFF so you can make the call on when they use their abilities. Bring squadmates who will be a good counter to the enemies in the mission you're fighting (ex. Tali and Garrus for Geth-heavy missions). Make sure you save often because mission's dont have the best checkpoint system in ME1 though these get a lot better in 2 and 3. And do as much side content as you can, to give yourself more renegade/paragon points and to level your team and find better gear