Organization... arguably the most important part of an academically successful high school career. If you're not already somewhat organized, it's time to get going. Staying organized allows you to work more efficiently and quickly access anything you might need.
One good way to stay organized is to have a different binder for every one of your classes. Label each binder accordingly, and if you wanna get fancy go ahead and color code them too. Having to carry around 4 or 6 binders (depending on if you're on a block schedule) can seem like a lot and unnecessary, but it may just be more helpful than you first suspect. Having separate binders allows you to ensure that all the papers and references you need for that class will be in that binder, and not in a miscellaneous folder or crammed in one huge binder. It's also a good idea to go ahead and buy a light/compact 3 ring hole puncher you can use to avoid having a bunch of papers stuffed on the inside pockets of your binders. Now that you've organized your binders by class, go ahead and start organizing each individual binder by separating it into sections to place similar items together. For this I would highly recommend insertable dividers. Now you can make sections to differentiate between homework, notes, classwork, tests, and extra paper.
Another great way to stay organized is to keep a calendar or planner. By having a calendar you have all the dates you need in one place and not scattered around your notes among various classes. Calendars can also help you to better plan and use your time wisely. Half the time people procrastinate is because they don't even know when an assignment is due and just assume they have time. A planner or calendar will help you to identify when it's appropriate to begin a project or studying. With this kind of organization you'll be able to plan ahead and know that you need to go ahead and get this knocked out because tomorrow you'll be swamped.
It's a good idea to go ahead and have a designated spot for your pins and pencils. There's nothing worse than getting to a class and realizing that you don't have anything to take notes with. So go ahead and either decide to have a spot in your backpack or buy an inexpensive pencil pouch. Be sure that at the end of every class you return the writing utensil you took out, this way you don't wind up constantly loosing your pens and pencils.
Last but not least, DATE YOUR NOTES! Dating your notes can help you to easily find the material your looking for to study with. A simple date in the upper right hand corner before you start class can go along way to keeping you organized.