To stay focused and increase your concentration you need to set some goals or a aim we can say. Once a aim is set ,you are dedicated to work on it. Writing those goals on a sticky note and putting it upon your study table will really be helpful. Because whenever you sit to study and you see that goal written there on your table you will get motivated to work for it. Else meditation can really be helpful.

Hello student its very important to stay peaceful and calm so that you can study with full concentration. To stay peaceful and relax you must drink plenty of water because you need to stay hydrated do do some yoga/meditation in the morning that help you all day to stay calm and relax.

You must get a good and sound sleep you should take atleast 7-8 hours of sound sleep.

And most important use Electronics gadgets such as mobile phone tablet TV Games PSP as less as possible.

Feel free to comment if you have any doubt

Good luck