Make a daily to-do list and prioritize important tasks and assignments. This will help you concentrate more quickly. Do NOT get too comfortable. You want your mind to be alert and your eyes open. Use the library.
Most students get more done in shorter periods of time in the library.
Find a quiet place to study so noise does not interrupt studying. Set-up study groups. They assist in articulating concepts and most important, avoiding procrastination. When your concentration is broken, take a 15 minute break. If necessary, find a new place to study or perhaps even a new time.