There is no hard and fast rule to study with concentration.
But with little dedication you can create your own concentration during study.
First of all when you start to study never imagine any fixed study time like “I need to study 2 hours min” or “I need to study 3 hours min”. If you do like this you will be constantly looking towards the clock and now and then your concentration will break.
Second thing is that remove all the electronics gadgets from you study room and never bring your phone to the study room. Make it a rule.
Third thing at first when you try to concentrate many different thoughts will come into mind. Don’t block them just replace those thoughts with questions like “Why I need to study?” or “Which things I will buy once I have a job?” etc.
Fourth thing when you are starting to concentrate and something breaks your concentration do not worry again start reading the previous things. Read things again and again until you can understand or your concentration builds up.
Fifth thing is to write the same thing down in a paper when your concentration is breaking more often. Write multiple no of times.
Sixth thing is you would need patience. That is the most controlling factor for your concentration build up.
Seventh thing is to remember a proper study involves three things- look, read, write. Do these things in that order only. For example you want to read a chapter then look at the pictures if any at first then read the topic you want to study out loud and finally once done reading write down the important points from the topic and again read what you wrote.
That would be all. In short you would need courage to stay away from gadgets 😉 to have patience and finally the correct state of mind to absorb the concepts and to never force yourself to study. If you do not want to read at this particular time then just go out of the house but the time spent out should be equalized with same amount of study.
Enjoy Studying !!!