Get lotsa new folders and notebooks to start off. Give yourself a clean slate. Date everything, keep track of any pages you may take out of these things, and don't fall behind in classwork. For school, that is. The same thing applies for home - give yourself a clean slate. Break out the boxes, place everything in them, then sort. Find a place for everything. Throw out what you don't need. And try not to get discouraged either, or you'll just have a larger mess on your hands. And don't throw out anything important. :o
But getting orgnized is a completely different thing than staying organized. Like anything else, though, you should work at it if you want to improve.
And I advise strongly agianst just cramming everything into one folder or box and hiding it somewhere. Eventually you'll run out of room. :c
