The Pomodoro technique is one of the most well-known time-management methodologies. As per this technique, you work for 25 minutes followed by a short 3-5 minute break. You repeat the same cycle 4 times and take a longer break.
The simplicity of the technique is the primary reason why it works effectively for most people.
This short 20-paged book contains a detailed guide on how to implement the method in real life. It also provides useful pointers and answers to frequently asked questions.