I like the idea, and would be happy to contribute.
I guess we would first need to settle on a plan for the guide. It could be a series of short pieces on different types of audience, different projects and so on, a bit like the Royal Geographical Society guide. Or it could be a wiki with ideas, examples of projects, and so on, probably under the direction of an editor who would keep everything in good order and preserve a clear tree structure for the benefit of people who like to view collections of ideas and examples that way (with cross-links for people who do not like working up and down trees, or who want to browse serendipitously). Or there may be other possible structures.