If the direct route (telling them what works and what doesn't, etc.), this might. I read this in a book (and right now I can't remember which one!).
Meet with the person and tell them that you are available for help whenever they need it. All they have to do is ask (trust me, eventually they will). The secret is to then ASK THEM "What do you want me to do right now?" Chances are the first answer will be "Just let me do my job". If that's the case, then say something like "OK, I will sit back and wait for you to come to me. I am on your side, just let me know what you need me to do" Then when they do come to you (and they will!) don't TELL them what to do, ask them questions to lead them to the right answer. Example: "What does our risk management statement say about this? What is your gut telling you to do? If you wait until Friday to book the room, what do you think will happen?" Question them about the details that you know should be planned, and let them hear their answers (and how bad they might sound).
The whole idea is to guide them to coming up with the answer themselves. Add in stories about "Well, when I was planning that, this is what happened." And there will be appropriate times to say "Absolutely not. That is against our Constitution. It's on page 27"
This is hard to explain just by reading it. It's easier to explain in person, so I hope I don't sound crazy in this post!!!