I've also found that having a laptop with you with your preferred IDE ready to go is a great idea. I suck at hand writing but type like a champ, and feel that "whiteboard" coding is more of an exercise for those who were TAs in college than someone who can show how to really code in person.

About 1/2 the time my suggestion to write live code was shot down. I do fine on the whiteboard, just hate it.