There is something called PATS Model in Psychology which the University of Toronto has published some time back.

1. Picking the Best Environment for you to study: This is important because you should feel secure and comfortable but not too comfortable where you might fall asleep.
2. Always reducing the visual distractions: Make sure you have nothing within your vicinity to distract you. Like keep your phone a side. Or sit away from the TV, Windows where you can see people.
3. Try to Eliminate Noise around you: If you are someone who can concentrate with music, make sure it is light music and nothing to distract you. It should increase your ability to concentrate and not distract you. If there is any noise that might distract you, use ear plugs or a fan. Trust me, if am being distracted by noise, I switch on the fan and it works.
4. Self talk to control Internal Distractions: When you are noticing that the mind is drifting aside, stop what you are upto and keep a checkmark on a piece of paper along with the time. Keep a track of these checkmarks and the timings. Talk to yourself that you understand you are being distracted but you also have to study. If it keeps bothering you, write down what is it that is bothering you and promise yourself that you will come back and look into that. Now that has been parked in the notebook, get back to studying.

Few tips you always need to remember are:

• You need to be physically fit to be prepared for what is ahead of you.
• Keep telling yourself that you can. That is important
• Make sure you improve on the speed in solving sample papers and quizzes
• Take online mock tests
• Focus on accuracy and speed as well
• Improve your concepts and focus on weaker areas
• Short breaks between change of subjects is really important
• Do not overstress yourself
• Avoid oversleeping during the day but get adequate sleep
• Dont get nervous.