In normal games, I try to play the best I can to win, but I will often have bad champions or bad items, and attempt to do the best I can with those. Helps me learn a lot, and is a lot of fun. Boy do I was wish All Random was in Normal games by now.
For me, that's the difference between Ranked and Normal: Ranked, you play optimally, you choose optimally, you build optimally. Normal, you play optimally, you choose and build whatever you want, because it doesn't really matter if it turns out to be ineffective.