Agree with Slipstream. Have all the necessary documents ready - course completion certificate, course record folder, passport, licence, medical. Do the perf calculations iaw your Operations Manual; that will usually mean doing them iaw Part-CAT (applying the appropriate safety factors) as you're training to be a commercial pilot. Give a weather brief using the Met Forms 215 and 214; have the latest TAFS and METARS available on your iPad. Know your way around the aircraft documents - things like the Release to Service. Know what you need to carry on board - the POH, MEL and interception procedures as a minimum. Find out how your examiner likes their tea/coffee!