“To be a good guide you need to have the qualities of a storyteller, but you should not be one.”
I always resist the temptation of “inventing” answers and telling fantastic stories to entertain rather than to inform.
Official Guides with a government approved license in Mexico must complete three years of school lectures and must continue their instruction by taking 160 hours of lectures on different subjects to renew their guide license every 4 years.
Be very careful. There are many who offer tourist guide services who are not officially licensed guides. This practice is forbidden by law, and tourists using these guides do not have the guaranties and protections offered by officially licensed guides with their services.
Knowledge is very important for guides, but it is not the only important thing. As a guide, one has to be able to detect the particular needs of the visitors and try to satisfy those needs. There is no point in taking a person for hours to an archaeological site, for example, if her primary interest is visiting handicrafts workshops.