When I went exploring (using AltaVista, of course) for occurrences of the phrase 'teach by example' I was surprised to find that the largest group was religious in orientation and content. My intent is entirely secular, and summed up in the phrase "...be seen to be a learner...". I'm still searching for statements that are sincere without being sanctimonious or clichéed. Here's one from a U. Mass 'nature study' weblet. It's remarkable how many of the 'tips' can be reworded to apply as well to college students.

Tip for Teachers

The most important goal in nature studies is to establish an emotional link between the students and the natural world, Being curious and comfortable, in a natural setting, will lead to exploration and a desire for information. Here are a few tips for environmental educators:
We want to inspire students with visions of the delight and wonder and challenge of striving to understand the workings of the world. The single best way to so inspire is by the example of our own lives, enthusiasm, and work. One of the nicest things about Washington and Lee is that librarians aren't compartmentalized and shut out of the possibility to participate in this way.