Manage your time properly in the exam
This is the most vital of all techniques. The people who write the exam papers, sit in drafty attics devising fresh new exam tortures are nothing if not clever. They have loads of different ways of tripping you up. The one they use most often is to make you spend way too much time on the first question. Be wary of this! Many very clever students blow their chances by spending an hour on the first question when it is only worth two marks.
Make sure you spend the most time on the questions that have the most marks. Often these are the last ones, and there is a very solid argument for looking at the paper first, seeing which questions carry the fat marks, and doing these first.