Well you'd be advised to download the PPL syllabus and familiarise yourself with the air exercises you've covered - as a good starting point. Then, you could get a copy of the examiners check sheet for the test itself and make sure you know what to expect altho the exmainer will fully brief you prior to the test on the day. My biggest peice of advice is not to forget the carb ice checks so FREDA checks every 5-10 minutes or, whenever you have a quiet moment - the examiner will not penalise you for it!
Good luck,
VFE.