So you're sitting in your room. You've taken some finals and have another one right around the corner. You focused all your time and energy on studying or "studying" for the first exam. Your body aches with random pains, you're running on like four hours of sleep. What should you do?
Step 1: Get off the freaking bed! Now is not the time to sleep.
Step 2: Gather all your previous tests and whatever other practice material you have.
Step 3: Leave your room. You need to go to the library or a quiet place that you don't associate with comfort. Being in your bedroom always has the temptation of laying on your bed. How many times have you said to yourself, "I'll just study on my bed" and just ended up on your phone or sleeping? Being in a place like the library puts you in a studious environment. Especially if you are a college student, going to study in the library really motivates you to study because all those around you are studying.
Step 4: Split your time up between doing practice problems and going over notes. If you don't have a general study schedule planned out, it's very hard to know what exactly you need to do to study. Making a schedule allows you to focus your mind on one activity at a time.
Step 5: Schedule in timed breaks! You can't just be like, "I'm going to stop working for five minutes." Those "five" minutes are never really five minutes. You need to be firm with yourself and say, "Okay, from 10:15 to 10:30 I will take a break, but at 10:30, I need to start the second practice exam."
Step 6: The most important thing you need to do is not give up hope. If you only have three days until that big chemistry final, then so be it. Focus on reviewing what you know. Understand all that you can. And take the practice exams given to you seriously. Questions on your final will be similar to the tests you were given.
Step 7: Get enough sleep the night before! Pulling an all-nighter before a big test is not the way to go. After a certain amount of time, your brain won't hold any more information you try to store in it. It will close for the night and you need to sleep so what you did study that day is still fresh in your mind when you wake up.