For me, if I cant see a way out, or have a clue what to do, then I talk to my little sister. She is a wise head on young shoulders and always seems to see the things in the problem that I dont and offers the best advice I know. My mum is much better at sorting out serious things, the things Im worrying about the most.
I think its mainly the person you are closest too, who you spend the most time with, as they see the effects its having on you, whether you're down etc. They also know most about you so know how you would feel, and the things you would and wouldnt do in any situation.
Sometimes I talk to a total stranger who happens to ask how I am, as sometimes I feel they have a totally un biased opinion and may offer good advice(: