Always:
Peace with Geth and Quarian
Wrex in ME1 saved (because of Citadel DLC... When it came out, I replayed the whole trilogy with my Psychotic Renegade Shepard that killed everyone and everything), so that leads to Mordin dying and Genophage Cured.
Punch Merc out of the Window
Paragon Interrupt in the end of Project Overlord, which was led by Not allowing Project Overlord Continue (Shep may be a psychotic, but not THAT psychotic)
"You talk too much" Renegade Option
Shooting Udina
Picking Renegade with Udina/calling him a bastard (Yes, because of ME1. Shepard got pissed)
Edit: Punching Manuel AND the Pyjak 
Never:
Uh... IDK? The contrary of the above things? 
J/k, it's 'cause I can't remember much details... Need to make a different playthrough this time, I always end up doing the same thing as in my last playthrough...