I usually go full paragon on the characters I like (Squadmates, Anderson, etc.) but full renegade on anyone I don't like (Saren, TIM). Romancing Liara in ME1, then going for Tali in ME2 and ME3. Leading Garrus on the "good" path. Saving the council. Geth/Quarian alliance. Curing the genophage. Synthesis.
I tried to play it different many times, but in the end I just can't help myself but to stick to these points.