How to study properly? What are its basics? And How to get full attention?

For a CBSE student, attention to details would prove helpful. If you are a political science student, keeping up with news and current affairs will be the icing on the cake. To score marks, always add a paragraph of introduction and conclusion to long answers and write in bullet points, highlighting keywords.

Just feel your self at that situation—all studies are related to the practical field. So feel yourself at that position and research and think that you are asked to solve situations based on that topic each time. Feel that you are going to give a lecture on that topic to people who don't know that and you have to make them understand. So what will you say to them about that topic? It will help.

Good Luck!

First think about your motive to study if you will not start the study, then what happens after one year because you cannot reverse the time. No magic will happen if we don't care for the time; we fail or get bad marks, and if you are not ok with this result, get up and start. There is no shortcut of success; if you want to get it right away, it is my personal experience.
Just make a timetable for you and try to stick to it for one month then you will be habitual. It isn't easy in starting, but you will enjoy it after some time. Fix hours for study and promise to yourself to first complete your tasks before enjoying your day. Also, you can take a small gap while studying.

First of all, know your strengths and weakness.
Take a book or paper and note them down. First, complete your weakness part because the strength part you can do at last because you are good at it.
So coming to the point of basics, first study any topic thoroughly. The second time you learn, you will remember some points of the first study; note them down in a notebook, and then study for the third time again. Now make notes of important points, that topic will be fixed in your mind.
Make a timetable of what you need to study. Study for a long time but not continuously, take small breaks every 30 minutes to one hour, go for a walk listen to feel-good music, then start studying again, trust me after listening to music if you study. You will get a concentration. If you need proper attention close your eyes for 5-10 minutes, do some meditation so that your energy levels will get boosted up. If you are interested you can do some basic yoga; it will also boost your mind and soul and give you good energy and full concentration in what work you are doing. Study well all the best for your future.

Dear Kajal,
First of all, you should never distress yourself thinking about your inefficiency and lack of concentration during studies. No one can get a cent per cent concentration while studying. It instead becomes distressful when you force yourself to learn. Instead, you should calm your mind and get the best of your mood to think clearly and better understand the concepts.
A well-disciplined study plan and timetable has to be made. Set goals everyday attainable by you, rather than keeping impossible goals which only further demotivate you and will end up devastated. It is always essential to make the concepts clearer to you rather than rushing through topics.
I would recommend you to spend daily at least 15 mins doing yoga which undoubtedly will improve your concentration to its peaks. It would help if you also spent time introspecting where you are slacking and sorting out problems that distract you.
Class 11th and 12th provide the necessary foundation for the courses you wish to master in the future. It is essential to give your best effort to embrace the concepts and better understand the course every time you go through it.