Study at regular times
Knowing when and what you are going to study saves you time and energy. Set specific study goals. Instead of "study chemistry", plan to "complete ten equations" or "read and take notes on chapter 6".
Study as soon after your lecture as possible
Review lecture notes and start assignments while the information is still fresh in your mind.
Keep study blocks short
Do not sit and study for long stretches. Instead, alternate study sessions with breaks. The Pomodoro Technique is a popular approach to this study style. Using the Pomodoro Technique or something similar can help improve concentration.
Use “down time”
Time spent with very limited options for going anywhere else is "down time." Commuting on the bus and doing laundry in a laundromat are examples. Use “down time” to review notes, jot down ideas for a paper, or preview a textbook chapter. Avoid simply letting the time pass by.