1) List out what you have to do in priority order
This may seem unnecessary. However, many students have no clear idea what to do through a day. They just know they have to study. So they pick random topics from random subjects to study. That is not the way. Plan out your objectives for the day. This makes it easier and more satisfying for you to achieve them.
2) Create a time schedule for the above goals
This means you have a time slot for different goals. This also means you need to have the discipline to stick to the timings.
3) Be realistic
Don't overestimate what you can do in 24 hours.
4) Avoid distractions
Put your phone away! Stay away from your bed!
5) Exercise or rest in between study sessions
Exercise boosts your brain power. Put aside a good 10-20 minutes between each study session to focus on your state of mind.