I'm such a "need to get the best ending" whore for ME3 I'm spoiling myself of important decisions for the sake of knowing what to do. I know it sucks, but I only do it with this game. CURSE YOU INTERNET
The way I get around that is that my first playthrough is always a "whatever the hell I feel like doing at the time" playthrough (which tends to end up me being mostly paragon but not taking shit from anyone). Then I go through and do the "perfect" playthroughs afterward.