For revision purpose practice previous year papers and the pre board papers of various icse schools as they give you an idea about what type of questions can be asked and help you in knowing the paper pattern.Read the textbook as much as you can as topics from the textbook are only asked and write all the important keywords in the answer to score maximum marks.Practice numericals for physics and and chemistry as they have a high weightage.Try solving popular guide books as well for revision purpose.