I agree with Jim about getting into a routine to get yourself ready for a flight. It's probably not real important exactly what it is, just do the same thing so it all feels familliar.
When my helper puts the airplane down I give her a nod, arm the ESC, take a deep breath and get squared up to the center line. I try to do the same turnarounds as in practice and try to recognize that it's just like practice. I try to make the judges vanish until I've landed.

The other thing that Jim hasn't mentioned is that he's been working hard the last few years. Nothing calms the nerves like being prepared.

Scott