Q: How can I manage my time better?
A: There are very few methods of managing time that are universally applicable. Everyone has their own concerns, strengths, weaknesses, and quirks that dictate how they might best spend their time. Short of personal advising, most generalizations are obvious, like simply scheduling and prioritizing. In place of reiterating these, here are 5 less than obvious ways to manage your time on academic activities:
1) Do not be too stubborn. This sounds obvious at first, but it goes against the most obvious typical advice: motivation. If you get completely stuck on something for more than 10 or so minutes, do not just attempt to power through it. Try random things that are only plausible methods and see where it takes you. Do not be afraid to ask other people for help. Better yet, try to explain it to someone else in the same situation and you may be surprised that it starts making a whole lot more sense. When all else fails, go do something else, productive or not. This goes hand in hand with the typical advice to start early, but even last minute panic can be combated by temporarily giving up.
2) Stay calm. If you always work as fast as you can, you will almost certainly progress slower overall. What matters is that you keep progressing, not how fast you progress. This sounds like the generic turtle/hare fable, but it must be emphasized because it is contrary to what people tend to expect when it comes to time management.
3) Stop working and think. Typical advice and even the prior two notes seem to agree that it is important to step back from your academics from time to time to get it all out of your mind. What should really be advised is to stop actively working, but to always keep something productive in your thoughts. Do not close your mind to the opportunity to solve or even memorize something while you doing something entirely unrelated.
4) Just keep going. Simply beginning work is typically the hardest part of anything productive. Once you break through that interface and get started, feel free to slow down, take breaks, and give up as much as you want, but never actually stop entirely. For example, you may have some packet of questions to answer. Begin as soon as you receive them and act like you are taking a test. Answer the maybe 4% you actually can and get half of it wrong for all you know and then go do something else productive. Naturally return to the assignment every chance you are able and without something more important to do. Talk about it with people conversationally, even if they do not have to do it. Even if it is just calculations or memorization, make it sound interesting and you will magically feel inclined to spend time on it.
5) Be flexible. Make all the schedules you want, but never expect to follow them perfectly. Take advantage of anything unexpected to make progress on whatever is most convenient for the situation. Combining this with the other four points, just be diligent and opportunistic. You may not always be able to try harder in a given situation, but you can always find something else productive to do that is more worth your particular time.
One more thing to note: depression can be a real thing, and not just something you can get over like laziness. It tends to be a major cause of bad time management and the main reason people are not just able to succeed solely by trying harder.