Manage a specific study area for yourself, which should be clean and free from unwanted stuff. It will create a habit of studying, so that your mind will be more focused when you study in that zone.
Fix various time slots of 25 minutes of work and a gap of 5 minutes for rest. Practice this to make yourself free from burnout. After every 4 slots, take a long break of 20 to 25 minutes.
Turn off all unnecessary notifications on your device.If you have a computer, try to collect all your materials from there rather than using your phone for the information.
Passive reading leads to wandering of the mind. Instead, actively engage yourself in the learning, take notes, ask questions, and explain your learning to another available person in your surroundings.
Experiment with different kinds of music with no lyrics at all to boost your focus towards your learning. Music helps to calm the mind and leads to concentrated sessions.
Instead of using your phone during breaks, switch your activity to a short 5-minute walk or stretching. This will help in the flow of blood to your brain and improve concentration.
Focus on the process of your breathing; concentrate on the sound of your inhale and exhale. This will help in redirecting your focus and help in enhancing your attention span.
Before you begin your study, set a focused target for yourself. Instead of writing, read history; pick a chapter to read from that book, briefly go through the planning first, and then work on it.