I myself has secured above 90% in my CBSE boards in science stream with PCB.With boards I was also preparing for my medical entrance exam like neet and cleared it as well.So, I would like to give some tips that I have personally followed:-
1.Avoid social media and just strictly stay away from using WhatsApp.Use phone as a boon to watch useful videos on youtube or to search something useful from Google.
2.Just follow ncert . It’s your Bible.Read and learn as much as you can.
3.Make short notes of every chapter for your last minute revision.Or highlight the important lines of ncert.Don’t highlight the whole chapter.
So, these are some of my tips.If you have any doubt, comment below.