As a professional Math Tutor for many years, I can provide some of the best ways for students to learn as well as study tips and recommendations on what has worked for different students.
Before class
Organize your materials and write down a question or two about the last topic. Even if you don't have the opportunity to ask your questions, it's useful to formulate them because it makes you think! Often times your question will be answered by another student before you even ask it or even better - you'll discover it on your own.
Read through some examples ahead of time. Use material to be covered and attempt some problems (even if you can't do them correctly, you're starting to think about the material - class will make a lot more sense when you do this).
In class
Even if you don't think your teacher is the best, you can learn a lot in class. Class is the best place to learn what material you will be responsible for. Teachers often skip sections in textbooks, cover sections not in the textbooks, or teach alternate methods.
Ask questions. This is the most effective way to learn. It requires you to think!
Take detailed notes. Date them and write down questions you have in them.
At home
Studying should not make you tired! If you find yourself drowsy while studying, you need to change something. Following are some techniques to experiment with so you can figure out what works best for you. Your goal should be to learn as much as possible in the minimum amount of time.
Get (and stay) organized - Five minutes of organization/day will save you over triple that time wasted looking for items, let alone the credit you lose by not turning in assignments. You don't have to be unpleasantly surprised for a surprise open notebook test.
Find out what time of day works best for you to study. This is different than what time of day you prefer (never). Dedicate a block of time that you can commit to five days/week to a certain subject. Experiment with a given time (try 30 minutes per day) for a week before deciding it doesn't work. Try everything from early afternoon to before dinner or after dinner to before school. Turn off all of your phones and don't let anyone bother you.
Studying does not have to be a quiet activity. Quiet activities make many people sleepy. A quiet atmosphere works well for certain people. Those people do well in libraries. Low volume background noise such as music or crashing waves can drown out other distractions like phones, people talking, airplanes, cars, etc. Talking out loud while studying helps many.
You don't have to study alone - find a study partner that doesn't know it all. We learn more effectively through discussion and teaching than listening to someone else (even someone that knows the material inside and out). You'll be surprised how much more you understand after explaining a concept to someone.
You don't have to sit still. You may try standing for alternate problems. Try lying down (for a short period). Whatever you're doing, if you nod off, change something! Get up and grab a drink. Snacking on something is beneficial for two reasons: 1. You rarely see someone fall asleep while eating a Popsicle. 2. Your brain runs on glucose, it's hard to focus if you're hungry.
Don't dwell on what you don't understand. That's what you do on tests, right? If you don't understand something after several minutes, formulate a detailed question (not "how do I do this problem?", but "why doesn't xyz formula work for this problem?" for example), write it down and move on. You can ask your question later or (more than likely) you'll discover the answer on your own in another problem or example.
Limit the time you spend on homework. Turn part of your homework into a timed quiz. It keeps you focused and helps you spend less time doing it. Try doing half of an assignment using your resources like notes, textbook, and examples. Treat the other half like a quiz. Time and grade it. It's ok if you don't do very well. You're just getting use to actual test conditions. The more experience you have under pressure, the better you perform on actual quizzes and tests.
Don't believe everything your teacher says. There's a difference between believing and understanding. To understand a new concept, you have to question and discuss the material. If you simply believe your teacher, you don't allow yourself the opportunity to think about the material (which is how you learn). Teachers understand the material because they've discussed it and they've taught it. They learn through teaching.
Grade your own work. Don't wait until you turn something into your teacher. You should "know what you don't know" after and during every assignment!
Don't study longer, study better! Ask your teacher how much time they expect you to put into this class to get the grade you want (of course it will vary but get a window). If you're in the ballpark and it's not cutting it - study smarter! Try these techniques and note what works for you. Ask others what they've tried. Get creative. Make it fun. It may not exactly be "cool" to get excited about studying, but it's pretty cool to get the grades you want, get into the college you want and have a life too!
Seek help. If your teacher is not able to provide the help you need (try one-to-one before ruling this out), and your parents don't quite cut it - hire a tutor. A professional tutor has a lot of experience dealing with people in every scenario from turning a B into an A, to just passing a class.
Learning is an active process. The above tips are to help students become more engaged in the process. Most importantly, the purpose of studying is to learn as much relevant material as possible in the minimum amount of time.
