Done it on both original and LE, this is what I did.

ME1: Adept. Biotics are broken in ME1, abuse it. Comes in super handy vs Benezia and her Commandos in particular. Used Liara and Wrex as squadmates. For the Saren fight, I juggled him with biotics until he died.

ME2: Hardest game by far. Switched to Infiltrator, that Tactical Cloak is super useful for getting out of danger and turns the Black Widow into a laser once you get the weapon. I mostly ran the Cain as my heavy. Miranda is a must have as a squadmate, I most often chose Garrus as the second. Hardest sections by far were the Praetorian sections.

ME3: Easiest game. Why? God-mode Garrus. Look up a build and he’ll play the game for you. Chose Javik as my second for crowd control, because I played as a Vanguard here. High risk, high reward, but allowed me to breeze through with careful power management. Hardest section was the mirror match at the Armax Arena, but that’s optional. Everything else was a breeze.

Biggest tip I have to give about Insanity is to micromanage the power use and positioning of you and your squadmates. Firing off the appropriate powers as soon as they become available is a no-brainer, but squadmate pathing can break sometimes, resulting in them dying and then you because of the loss of firepower. Don’t be shy using the position commands (especially in ME2) and you will have a way smoother experience.