4-Use the Pomodoro Technique
This is a good system that helps you avoid procrastination.
How it works is that you have to work 25 minutes and you stop. Then you rest 5 minutes and start over again for another 25 minutes.
After you do 4 of those, you can rest half an hour. This is just one of the techniques used in Pomodoro.
This is a technique that works for many people.