I would focus on safety first. Especially if he has some background driving watersports. Just like anything, people develop bad habits that they don't even notice. Listen to the first few minutes of the spraymakers podcast on driving. You don't need to go into the course rhythm but the discussion on turning the boat off, Predicting where the boat may float to when a skier is getting ready, basic communications is all good.
As far as pulling up skiers, every skier and boat is going to be different. Just getting practice. Key is make sure the slack is out and you roll the throttle smoothly.