It is great that you seek to be more than just a student. To be better at anything involves time, dedication and self-discipline. Do your reading assignments ahead of the class, so that what your teacher teaches on makes more sense to you and you are more equip to ask intelligent questions to gain a deeper understanding and appreciation of the material being taught. Don't be afraid to ask questions when you do not understand - regardless of what others may think, since you purpose in your heart to learn the material and do well at it.
Review your notes same day and do practice questions each week especially on the areas where you do not excel well in. Try tutoring someone to reinforce what have been taught to you. Also, it will help you better understand the material as well. When you do this on a consistent basis, it will require less effort to prepare for exams as the time approaches since you started this process earlier.
Start your assignment when they are given, so you don't end up rushing it last minute. Give thought to your approach to the assignment and plan out your time properly so that you complete it well before the due date. This will help if there is some unforeseen delay and you would still have time to complete assignment.
I'm sure you will not just be a good student, but a great one!
All the best!