If this looks like the contents that may or may not have been "released" from the confines of the backpack (or perhaps it's more crumpled), it is time to employ some binders. How the binder is organized is up to you. I like to use page protectors with a tab made of a label or labelled masking tape to separate topics. Then I put my "Work in Progress" inside the page protector.
Don't throw out notes until the end of the semester. They may be needed for study purposes.
Test anxiety is a very real thing. Many times it comes from feeling underprepared. So, going into a test with a plan can reduce that anxiety and give the best shot at success. Regular studying, not just when there is a test coming up, is the best way to prepare. Set aside a "homework hour." If there is no homework, use that time to choose a course and study all the material covered so far. If there is something confusing, make a note of it and ask the teacher questions the next day. For some effective study strategies, check out the guide below: