As a semi-veteran of journal writing (I've only done it for about the last ten years and I'm 32, which is relatively not that long compared to some), I recommend people writing in a journal. Well, I guess your bedroom wall would work too, but if you rent that could be a problem.
Anyways, the journal is a great storehouse for ideas made flesh in the form of words, instead of the electrical neural firings of one's brain. At least, when we write things down we can look at them and judge whether they are accurate or not. We also get in the practice of putting the brilliant statements we have in our minds, that often come out in conversation, into print. So when we do write a paper, poem, story, or essay for class it is a little easier, because we have become well practiced at translating our thoughts into linguistic signs!
I find, too, that a journal can be a place where, when I am stressed, I can vent and get some perspective on whatever is bothering me. It can also be a place to celebrate, express serenity or content, or to describe something funny or strange you witnessed. All in all, it is a great invention that writers have used generation after generation, and I highly recommend picking one up.