How to use your study time with the maximum efficiency? How to make the process of learning more enjoyable? Various things work for different people, but as your fellow student of physics for the last 25 years let me list those things that “clicked” for me. Use them, discard, or modify to suit your own personality and tastes.
1. “Read the textbook”. This seems trivial, but there are many ways to implement it. I recommend reading the textbook three times. First time you should read it before the lecture. The purpose is not so much to absorb everything as to grasp the main thrust -- the idea, conclusion, and main points of the derivation. Identify specific issues that baffle you and take them to the class. If the lecture still does help you to see the light bring the issue up, it is likely that many other students are as puzzled as you are. As soon after the class as possible read the textbook for the second time. Now try to make sense of everything in it. This is your main reading. You should feel that you have grasped the material. Then sit down to do the homework assignment. Most likely than not you will realize that your feeling was deceptive. Pay attention to what is giving you trouble now and refer back to the relevant parts of the textbook for the in-depth rethinking of them.
2. “Compound interest”. Time spend studying leads to the accumulation of knowledge that adds as compound interest. By this I mean that someone who spends 6 hours per day studying (not an enormous amount) will learn much more than a person of similar abilities who spends 5 hours a day, and not merely by 20%. After 4 years it will be more like (1.2)^4, which is roughly twice as much! The math here is for illustration only, but you have got the point.
3. “Fall in love”, with what you are learning that is. You will achieve much greater results if you study just for the sake of satisfying your curiosity than for a good grade. This is definitely the most difficult tip to implement as it is not easy to fall in love with something at will, but presumably you have chosen your field of study not without some consideration of your aptitudes. So try to play with the knowledge you are acquiring, by inventing your own assignments above those required. Apply what you learn to everyday things you see around. When you learn for the sake of learning you invariably learn more (and better) than the minimum expected of you. Do not forget that there is much more physics beyond the textbook.
4. “Teach others”. The best way to learn a difficult concept is by explaining it to other people. Very often you will realize how tentative your understanding is, which will force you to think more and deeper about it.
5. “Simplify”. When facing a difficult problem that you cannot solve outright, begin with its most simple form, stripping it down to the bare bones by removing complicating features, and solving that other problem first. (For example, when solving a capacitor problem, you might want to neglect fringe effects and then further "replace" the dielectric medium inside the capacitor with vacuum). Then put complicating features back in place, one by one. This might appear as a long way to solve two or three problems instead of one, but in reality this is more often than not a much faster way.
6. “See the bigger picture”. Always try building on what you already know and put pieces of new knowledge in perspective. How does it fit, improve, modify, or correct the picture you already have? Are there any new connections and analogies you can make? For example, what are the similarities and differences between Bio-Sawart and Coulomb laws? What would equipartition theorem of statistical mechanics entail for the motion of stars?
7. “Aim high”. We become what we think we are. If you believe that you can only solve simple problems, or earn only a “B” on the test that thought will become a self-fulfilling prophecy. Set bigger goals. Remember, bigger targets are easier to hit.
8. “Perfect is the enemy of good”. You will repeatedly be stuck on a difficult subject. When that happens avoid expending additional effort when you realize your returns are diminishing. This will stop you from becoming too frustrated. Move on to other things but return back later. Very often difficult concepts or methods of thinking need some time to sink in and to get internalized in your mind. Physics is not something you can cram into a couple of all-nighters before the end of semester, so allow plenty of time and plan your studying accordingly.
9. “Train as you compete”. In sports if you practice half-heartedly and then expect yourself to perform differently and more seriously during an important match, the outcome is usually a disappointment. The same applies to your education. If you always do your homework assignments at a leisurely pace or in groups with other students you cannot realistically expect that the timed exam environment (with added psychological pressure) is not going to be different. The most ubiquitous students’ complaint is that exams are more difficult than the homework. In fact they are very rarely so per se, but you make them harder by not practicing exam-taking under real conditions. So, at least sometimes (preferably regularly) you have to do your homework under the right conditions: alone and against the clock. This is going to be a much better predictor of your exam performance and a practice routine you could fall back upon mentally during the "match".
10. “If it feels comfortable you are not doing it right”. People have different talents and learn at different speeds. If you are one of the lucky fast learners a particular course might not be challenging for you. Feeling of comfort is a clear signal that you are not benefitting from the class as much as you could have. Using the same sports analogy a comfortable workout/practice at a fraction of your capacity is not going to advance your abilities. To achieve true gains you must find ways to make your learning more challenging. Fortunately, there is never a shortage of difficult problems in physics.