Find past paper questions on the topic you have revised and try them – firstly allowing yourself support, if need be, and without limits on time. Then, as you progress with your revision, complete questions without support and under exam timings.
Always mark questions using exam board mark schemes and note well any marks you lost. It is often useful to re-do questions later in the revision process so that you can see how your performance has improved – and that you have learned from mistakes you may have made the first time.
See Subject Information section for links to past paper practice