As a codriver I have this bit of advice.
DONT TAKE YOURSELF TOO SERIOUSLY!
My first event was a pretty big national event over here. It was my drivers first event as well. Im not here to bash the person but to tell you we had set out before hand, if mistakes were made ON EITHER END "dont sweat it!"
Needless to say the mistakes my driver made I took in stride and mattered not to me. The mistakes I made were made clear and yelling was common. (not fun to be in an hour long transit with no conversating) Treating your codriver like trash will only get you a bad rep for other codrivers. The same works in reverse I try to push drivers when I feel they could push harder and slow them down when they start to get erratic, but Ive never gotten out of hand.
The whole experience left a bad taste in my mouth but since then Ive codriven for much more experienced(calm and fast) drivers and had fun without the prima donna dramatics from a relative unknown.