What is seldom explained: accurate and reliable information on day-to-day living in the Project environment.

Don’t flood him/her with plenty of official information of no practical use; after all, the poor guy is interested on how to step in in the softest way.
That is usually overlooked and blocks the poor guy’s efficiency for some weeks.

Even when dealing with Project Management and a Project environment, never forget haste is  a bad habit: give Project people the time to get accustomed and, foremost of all, give them the right information.