All are invited to add their Commercial Checkride hints and tips here in this thread.
I left the commercial checkride unconquered for years because I just seemed to come up a brick wall of BS when trying it and found very little encouragement when seaching other threads on this subject.
I think the key point to this checkride is to do just exactly as you are asked to do by the lady test instructor - as opposed to how you where trained to do things in the commercial lessons - because they do not comply with each other. Also the preflight segment listing provided is totally incorrect.
1) For example, upon levelling out after a climb - we are trained to stay configured until we speed up to 170 - then reduce manifold - then reduce RPM - then close cowl flaps, whereas in this checkride upon levelling out after a climb - you reduce manifold, reduce RPM and close cowl flaps straight away before speeding up to 170.
2) All climbs in this checkride are to be at 120 knots instead of how we are trained at 136 knots.
Some added points - but I am not sure these are vital to success. I also thinned the mixture to about half when above approx 4500 ft.
When you are asked to perform high speed descent down to 1500 ft inbound to harvey field and not to exceed 22 inch manifold and not to exceed 200 knots - in my case I did not exceed 20.5 inches manifold and did not even reach 190 knots - but still passed the checkride.
I had the GPS open for the whole flight, but did not need to log a direct to harvey field in the GPS - simply follow the heading bug which is updated for you during the checkride.
There may be some confusion in the way you are asked to enter the downwind and land at harvey field, but I used the right turn pattern and landed on the left runway 14 with no problem.
So I hope more people are encouraged and give the commercial checkride a go. It is quite do-able and in some ways it is easier than the instrument checkride.