Of course, the more you study, the more you'll learn, so studying frequently is a good idea. But the sooner you start studying, the easier it will also be for you to remember everything. This means that you shouldn't start studying two or three days before an exam. Start work at least a week before an exam; and consider just studying continuously throughout the quarter if you feel like you need to. It's a good idea to go back over old information at the same time that you go over the information from this week too. This will help keep those older ideas and skills fresh in your mind so that you can build on them. There's nothing wrong with getting some help and getting expert advice that's tailored to your situation. It can seriously help you learn much faster. Put aside your shyness and your pride and ask your teacher for help. If they don't have time to help you, they should be able to help you at least find a tutor.  If you don't have money for a tutor, your teacher might be able to set you up with someone in your class who is doing well and can help you out. Many schools also have free tutoring centers.  Check those out if they're available. A mind map is a great way to burn whatever information you're trying to learn straight into your brain. A mind map is a visual representation of what you're trying to learn. Use note-cards, pictures, and sheets of paper to write out facts, explanations, and organized concepts. Now, pin the items on a wall or lay them out on a floor, placing similar items together and using string or other items to indicate linked ideas and subjects. Study from this map instead of just looking at your notes. When you go to take a test or write a paper, you'll be able to think back to your mind map and remember the information based on where it was and what it was connected to, just like how you can remember where things are on a geographical map. Memorizing isn't always the most foolproof technique, but it can help if you need to learn certain kinds of information very quickly....

TL;DR in Vietnamese:
Học bài càng sớm và càng thường xuyên càng tốt. Tìm sự giúp đỡ của gia sư dạy kèm hoặc giáo viên. Tạo bản đồ tư duy để đẩy nhanh quá trình học. Học thuộc lòng một cách hiệu quả để chốt lại nhanh các thông tin. Tự tạo ra ngữ cảnh mà bạn cảm thấy thú vị.