If you had a new guy and had an hour to pregame:

[rainmaker]

My no-games-under-my-belt days are not long gone and my memory of those first few games are still quite fresh. Some of the errors!! What helped me the most was a partner who did not step in without being asked, but did step in when asked. That first game, he said, "I will never override you, but if you look at me with that lost look, I"ll come in and bail you out." I know that's not According to Hoyle, but it was exactly what I needed.

For pre-game, I'd choose one rule to go over, such as 3-seconds, or the basics of travelling. And one court coverage issue, such as "Take the play that is coming toward you" or "Step down and out on the shot." That's about as much as anyone can be expected to remember.

The most important part is the post-game. Give the old love sandwich Compliment-suggestion-compliment. The compliments could be as vague as "I've never seen a rookie do better!" Or as specific as, "You got every block/charge correct!" Then go out for that cold one, and let him/her do all the rest of the talking.

At least, this is what would work best, if it was me.