If You Have Already Been Studying Already
During the last week or so do your best to continue studying at about the same level/intensity that you have been for the rest of your time. You should do a mix of mock tests and specific reviews—the mock test is to make sure your pacing and timing are correct, and the specific review is to fill any knowledge gaps you may have. If you have more than a day, and you want to know what is best to review, use any remaining official practice material over anything else because that will prepare you the best for your TOEFL experience.
It is also good to refine your plan for the writing and speaking sections. Have you developed a personal template or looked at our speaking and writing templates? Being ready to use tools like this will also be a big boon on test day!
Even though you should continue studying, it is a good idea to save the day before your exam for rest. Maybe glance over key structures or notes for 30 minutes or so, but don't push through anything harder. It is very important to maintain health and confidence—your disposition on test day can mean the difference between an excellent score and an average one, so take care of yourself! :)
If You Haven't Already Been Studying Already
You can't magically jump up several levels of English in a few days, but you can definitely make a concentrated effort to improve your TOEFL chances. The best thing you can do is analyze TOEFL structure and style. Learning the types of questions and how much time you have to answer them can be a huge help. So the first thing you should do is see the different types of questions. The best resource for this is the free official Interactive Sampler. That will give you a clear idea of what will be on your TOEFL.
After you do that, watch these four videos, because each video gives the top two tips for each section of the TOEFL, based on what students usually have trouble with: advice for reading, listening, speaking, and writing section advice
If you have a little more time after doing all that, our free Magoosh’s Guide to the TOEFL iBT explains the test in detail. Use that knowledge and strategy with the rest of the free official TOEFL practice. The better you know the format of the test, the more confident you can be in your performance on test day. Even with only a few days, those top tips in the advice videos above and in that eBook can mean a higher score!
Just like said above, make sure you gives yourself some time to rest and take care of your mental health. Your disposition on test day is important! :)