When teaching new students or a new style of dance to old students, don't rush into complicated moves that look great on the dance floor. The difficulty of these moves is likely more frustrating than encouraging for the students. For that reason, start with the basics. Students gain more confidence when able to execute simple moves flawlessly than when they can only do complicated moves poorly.
Everyone learns differently and absorbs information better when it is presented in a certain way. This applies when teaching dance as much as it does in the classroom. When you describe a dance, present it in a way so that all learning types can absorb it. Describe what the "feel" of the dance is, describe in analytical detail which body part moves when and how far it moves, draw diagrams or demonstrate the dance fully. This helps all types of learners quickly learn the moves.
All students have different bodies. Unless you teach in a professional environment where auditions eliminate all but the most perfect bodies, you will work with people with many individualistic body features. Don't provide generic instruction that is unsuitable for them. Watch your students, and spot what is prohibiting them from performing the movement as correctly as possible for their body type. Then, you can help correct them with information that is applicable and useful, rather than generic.
It is important to remember that dance is a physical discipline and that it follows the same basic principles as any other physical discipline. Proper warm-up and cool-down sessions before and after each lesson have the effect of helping to prevent injury, pain and helping make the dancers better. Also, emphasise the importance of conditioning and overall fitness outside of class to create better dancers.