Leave it to God

So as I've mentioned in an earlier post, I've decided to start refocusing my faith and getting back to having Christ as my center. Well, I've recently decided that I don't really give my problems or situations to God. I just go about it the way I think I should. Now, how exactly do you give yourself to God? I've struggled with this, because I've said prayers, and I've read devotionals...but what is it really that you need to do? How do you "Leave it to God"? I guess this is how I always used to interpret it: you can say prayers and ask God to do what you want to happen. OR you can pray and let the situation be and if it was "meant to be" it was "meant to be". But now I'm not so sure. God gave us free will. So we are able to make our own decisions about things. With that being said, I now believe that if we ask God to guide us toward the right decision, that can also be considered "leaving it to God". I just have so many "up-in-the-air" situations that I don't know what to do! Where do I go to school? What major should I choose? Am I ready for a emotional relationship? Am I ready for change? There is so much that I am unsure of...how do I leave it to God?!