I actually didn’t find the ME1 insanity achievement all that hard. Just make sure it’s your 2nd playthrough as a biotic. The ability to freeze someone but still deal damage allows you to, in ANY one-enemy situation, completely own the field of battle. And in any other situation you can at least lock away the most powerful enemy until you’re ready to deal with them. I killed Saren without taking a single point of damage.
I only couldn’t do one part, and that was a Geth trap where I was at the back of a mine shaft and had to fight out. However, it was because I went there almost first so hadn’t completely leveled up to 60 yet. I skipped it and when i came back nearer the end of the playthrough, I cut through them like butter.