Hey!There

For having 95% percentage in 10+2 in ICSE board,all you need to do go through each and every line of textbook.And keep revision regularly,you have enough time in boards examination.First try to cover each and every chapters,then do practice numericals and derivations as 30-40% contents are of numericals and derivations in boards.Aslo refer to previous years of board papers and do pratice it.

I hope this helps