If you are aiming to get top colleges of engineering you have to work hard as there is lot of competition to get top colleges like NITs/IITs and IIITs. You should be determined and self motivated to crack your exam. Try to focus in your study. Don't divert your mind. You can make your time -table, set your daily and weekly targets and try to follow them. You can also make your own notes it will build your concentration. You can join study group as well Good Luck!!