Teaching/developing troubleshooting skills

[Pete Kruckenberg <pete () kruckenberg com>]

I'm working on trying to teach others in my group (usually
less-experienced, but not always) how to improve their
large-network troubleshooting skills (the techniques of
isolating a problem, etc).

It's been so long since I learned network troubleshooting
techniques I can't remember how I learned them or even how I
used to do it (so poorly).

Does anyone have experience with developing a
skills-improvement program on this topic? If you've tried
such a thing, what worked/didn't work for you? Outside
training? Books? Mentoring? Motivational posters?

I'm particularly sensitive to the "I got my CCNA, therefore
I know everything there is to know about troubleshooting"  
perspective, and how to encourage improving troubleshooting
skills without making it insultingly basic.

Thanks for your help.
Pete.