Time Management
When you set aside time to do something, try to get it done without distractions. For example studying for an exam might take 6 hrs if you locked yourself in a room/library with cellphone off and no distractions. That same subject could take 6 days when you stop and chat, visit the fridge, “study” aka shmooze half the time with a friend, etc.
Oh, and never wait till last minute = cramming.
This has helped me get through 5+ years of college.