What are the most effective techniques to use when teaching adults at colleges?

You must use vision and listening ways like light board and computer with films and pictures with information and explain every things to studends and give the lictures to studends in their computers or print the lectures to adult  studends

teaching adults can be more intresting and easier if you can increase the level of interaction with your students. if both the parties i.e the teacher and the students feel comfortable to ask questions and quarries and discuss problems then the work is much more relaxed. so maintain tuning with your students.

Yes, teaching students at college level is easier than students at pre- primary level, but the most important thing is to have good rapport with them in addition to core subject knowledge and efficiency to deliver the same to them in easy understandable flow.