Someone explained to me that the rationale of the CPL flight test is not so much a test of your flying abilities as a test of your abilities to be a professional pilot. The examiner naturally assumes you can fly the aircraft to a high standard or else you wouldn't be there for the test. Of course if you cannot you won't pass but for the most part the majority of CPL flight test candidates are going to be competant pilots.
Where they go can wrong is in failing to take command of the aircraft. So the approach at all times is that you are pilot in command. That has to be you attitude from start to finish. So when it comes to passenger briefing, the detail is not so important as the way it's put across. If you're hesitant and stumbling over words, forgetting your lines etc. It won't inspire confidence.
Many examiners see it this way: 'Would I let this pilot fly my wife and children?'
Minor mistakes during a flight test are less important the the attitude of the candidate to the mistakes. Fail to show that you're pilot in command and it wil go bad for you. Be the Captain of the aircraft on that flight.