I just read an article from Ann Michael about what lessons she learned in a restaurant as a waitress:
All I needed to know about people I learned when I was a waitress.
When someone comes in, say hello. Do it quickly – even if you can’t get them what they want right way.
If someone shows up often, let them know you’ve noticed. Try to make them feel at home.
If someone asks you for something you don’t have, tell the truth.
[ read the full story: Manage To Change: Lessons from a Restaurant ]
One lesson that I learned: There is no wasted time – no matter what you do.
P.S. Ausnahmsweise mal in englisch ;-)