In order to prepare for the interview you should decide a topic in which you are comfortable as they will ask questions on your favourite topic. 

It is recommended to revise your board exam syllabus as it is important that your basics are clear. 

Practice a lot. So, that you are comfortable to speak in front of them.

Prepare to answer your hobbies, strength and weakness. 

Be comfortable at the the time of interview don't show them in case you are nervous.

Good luck!!