Here are a few tips on how to keep your teen organized (or try to anyway).
There needs to be a place for everything and keep everything in its place.
Keep things where they go after you have established a home for them. This is key. It is certainly easy to just toss things around instead of putting them back up but it saves time in the long run.
Teens need their own planner whether it be a daily list, a digital planner, or a paper planner. They can be as creative with this as they would like to be or as simple as they would like to be. It really does not matter. As long as things are being kept up with, there is no right or wrong.
Prioritizing: Let them figure out the "balance" of their subjects.
You might get different colored folders, notebooks, and colored tab dividers for each subject. This is a good way to organize things visually -i.e. a blue notebook for science.
Markers, highlighters, and colored pencils. I love them all and so do my girls. We have an endless supply of all of these.
So that is pretty much it. If you can commit to these few steps now, this will help stave off chaos for your teen later.