Hello,

Listen,if you are interseted in pursuing your B.Tech,then you must have given class 12th board exams,where you have studies all three P,C,M.

So before entering B.Tech,you should be thorough with your basic knowlege.

Integration should be on your tips(mainy indefinite),you should also be prepared with some chapters of chemistry and physics.

See,preparation before B.Tech is not that important,but preparation during the B.Tech is a very essential part.

Some students make a habbit of learning and studying just one or 2 days before the final exams.This is not a good thing for an engineer.So, make a point of studying regularly during your B.Tech course,because at the end no one will be there to look after your lame execuses,at the end the thing that matters is your overall performance,that we call as 'CGPA'.

You can also work for your spoken english,there are a variety of courses on the internet and some of the non-paid courses on 'You Tube' from where you can work for your spoken english,because at the last 'spoken english' is the only thing that will fetch you salaries and jobs.

Hope you Understood!

And if you want to prepare something before entering B.Tech,you can simply practice 'Integraton' in maths,basic 'Mechanics' (will be a subject in your 1st year only) and sometime can be given to chemistry.

Thank You 

All the Best!

If any queries,feel free to ask

Regards

Shikhar Singh Chauhan

Thia depends on what stream you have chosen. If you have gone for computer science, then the main subject is coding or programming. If you don't have much knowledge about that, then try to learn coding. Because this is the main thing in CS.
If you have chosen  electronics and communication, then try to learn some eletronics theory from google or books. In case electrical, try to learn circuit theory.
Cause, these are the main subjects of the respective streams. So try to study, because in college, professors are not going to teach you thoroughly.
Good luck..