A bit of soul seaching here..
It was all more than 15 years ago for me. I failed my first CPL GFT out of Bournemouth.
Although well prepared by my instructor, I felt nervous and possibly a bit intimidated by the examiner (my fault, not his). I filled in all the paperwork and worked out the flightplan, Wt & Balance etc but in my rush forgot to sign off the Tech Log. I was conscious of it on the back seat as we rolled and just wished I could have turned around and signed it. I was sure he was going to turn to me at any second and say 'you're flying illegally, you haven't signed for the a/c!' Of course he never did, but after the first leg (which in retrospect went well) I'd just got it in my mind that I'd failed, so sure enough I cocked up the partial panel and we went back to Hurn with my tail between my legs. Lots of expensive lessons learned;
if you plan for failure then you will,
pay attention to detail,
put a mistake behind you and get on with the future,
you are your own person, don't be put off by more senior people. I took a failure rather than a partial (daft but I'm glad I wiped the slate clean)
The second test at Bristol was a delight. He was signing the pink slip as we were turning final back to Lulsgate. He'd put me at my ease. I felt able to engage with him. Circuits done at Compton Abbas - great! At that stage I had minimum hours (I think about 150) for taking the CPL GFT so I was quite pleased with my achievement.
Tips? Well, the examiner isn't there to fail you. Let them pass you, it's up to you. Do as you've been told by your instructor, you might not agree with everything the CAA wants you to do, but if you want the licence, it's the only way! Your instructors want you to pass, they won't get any students if they all fail.
That all may be ancient history - let's see if anyone else has a more 'modern' view, but I suspect the basics are the same.
Good Luck to everyone about to embark on the Great Adventure.
Cheers,
TheOddOne