I think the best advice I was given, was not to give up hope. Even if you think it's gone wrong, keep on going.
On my skills test, I did the Nav first, and because the visibility was a bit on the marginal side, I soon became unsure of my position. I couldn't find the destination waypoint, and thought I'd failed. I told the examiner so. He gave me some hints, and so I climbed and did a few orbits, and hey presto, there it was! But I still thought I'd failed, and gave up hope (ignoring the advice I'd been given) but I did calm down significantly.
I made a bit of a mess-up in the handling section too. It took me ages to achieve slow flight, but I got there in the end. Everything else went okay, including the dreaded PFL.
I passed. Not partially, but fully.
The examiner told me that my nav skills were fine, and that he gave me the benefit of the doubt because of the por vis. He told me that my landings were really good, which, I was informed, was a good thing, because "half the battle with flying was getting the bloody thing back down."
One thing that I remember though, was that I was worried about my walk around checks. I was scared in case I missed anything out. But the examiner didn't even watch me. He sent me out, whilst he made a phone call.
Just remember, the examiner is not out to fail you, he (or she) is there to check that you're a safe pilot in good weather.
Good luck!
Flock