Hey,
Scoring 90% in Boards is a dream of every student.Its not always the students but families that want their children to score above 90 or 95 per cent.Well,it indeed is possible and easy to score good marks in Boards.
The key mantra for doing good in exams is that "Do your best and God will think of the rest". As cliched as it may sound but without hard work and dedication nothing is going to happen.I won't give you other  conventional tips which you must be getting from your family which you must listen but let's be honest,you are almost a month away from boards and  you really need to put in a lot of efforts.You are already done with 40 per cent and for 60 per cent you have a rough idea so utilise this time to pratice the previous year papers and analyse where you stand.Don't panick.Talk to your teachers and ask which chapter has more weightage and focus more on them. Work really hard bur dont stress yourself out.
Just remember a thing scoring 90% won't help you much as to get through the competition of life you need the practical learning.It's ultimately your hard work and analytical  skills which would help you in the long run
Hope this helps.
Good luck.

Hello Aspirant,

Getting 90 percentage in 12th is not that difficult now a days. The main thing is you should be strong enough with your basics so that you can able to  answer any question in your public exam even though you have not prepared it earlier. Practice as many number of previous year question papers so that you can get a brief  idea about the pattern. As you mentioned that you need to complete 60% of the remaining syllabus set a legitimate time table for it. Revise all the concepts and try to solve more examples.

Thank you!