This article has some good basic information on things to consider when designing lesson plans. It provides information on learning styles and teaching styles of students and instructors.
The article is specific to teaching the adult learner, and has a number of links that you can use for more information on specific topics.
I found the article a good starting point for planning a teaching experience with adults. It helped me assess my teaching style and identify my adult learning characteristics.
For more information on Andragogy by Malcolm Knowles follow this link, http://www.instructionaldesign.org/theories/andragogy.html