Despite the introvert thing, my best - and most enjoyable - studying happened when I found a few other motivated students and got together to do it. This was great for history, because we could debate the topics until we understood them. It was also great for math and physics, because we could share our understanding of how to approach the problems. Pizza is good, background music is good, distractions are not. Group study isn't a must, though.
Remember that part of studying is to get the information into your brain. INTPs need to see the whole of something and that takes time. There may be a time before or during the study where you aren't writing or doing anything obviously useful, but just sitting and pondering. You may even need to walk around and think about something else for a few minutes to let it settle. This isn't laziness; it is preparation. And research indicates that if you don't sleep, you won't retain it, so don't stay up all night.
Each class, teacher, and topic is different, so you have to adapt a bit. There will be some that interest you, or that you are better at, and others that you dislike. Don't give short shrift to any of them. Improving your strengths and shoring up weaknesses both matter.
And finally, if you do procrastinate and rush everything at the last minute, don't kick yourself for running out of time. Try not to leave it to the end, but remember that it happens, and it isn't the end of the world.