Solving previous year papers/sample papers or reference book's exercises is best way to review for exams. You could also take the help of any online website like www.tcyonline.com also

For last 5 years papers of CBSE Class 12 you could visit http://www.cbsewizard.com/cbse-class-xii/previous-year-papers/ they list subject-wise papers on their website in pdf form that are easy to access.