Your performance will be judged on both speed and accuracy, so aim to complete as many questions as you can.
At the beginning, glance at the whole test, see how many questions there are and work out how long that gives you for each one. Try to stick to this time limit as you go along, but remember that the questions are likely to get harder as the test progresses, so do them all as quickly as possible, particularly the early, simpler ones. Make sure you’re absolutely clear about what each question is asking before you answer.
These tests are usually deliberately designed so that the majority of the candidates don’t finish, so you’re likely to feel under pressure. If you are starting to get flustered, it may help to remind yourself that pressure is all part of the process and that everyone else taking the test will be feeling the heat just as much as you, however well they may be hiding it. Above all, try to stay calm, because getting in a panic doesn't help anyone.