Some good advice. I always have started out any adult class by asking them what they want to get out of the class. Then, if there are any clear goals, I structure my lessons for them in a way that lays out for them that they are learning what they've asked to learn. The say it three times approach: tell them what you're going to tell them, tell them, tell them what you've just told them. I do that for all classes, actually, but for adults I make a big deal out of showing them what I'm doing.
Above all, you need to keep adults engaged. It may be even more important than with kids. This is because an adult is likely to get less out of a class in the firts place, especially if it's not a class with clear learning objectives or goals, like conversation classes usually are, and because adults are both bussy and in charge of their own actions. No one can force them to sit through a class if they don't feel like it.
They need to stay interested and stay engaged, or they'll find lots of other things to do.