I was on a course we run called Learning That Lasts last week. I can recommend it highly.
One of the tenets of the course is that people learn best by doing, so the course teaches you how to teach in an interactive and hands-on way. Of course, the teaching on the course itself is interactive and hands-on. A significant part of the course is where every learner (as we like to now call ourselves - students study, but learners learn!) does a 40 minute presentation, which you then receive feedback on. It sounds scary, but isn't at all.
The course book is "Learning to Listen, Learning to Teach" by Jane Vella. Another book recommended was "The Accidental Trainer: You Know Computers, So They Want You to Teach Everyone Else". I think the subtitle says it all. I'm going to get a hold of that soon.