Learn the names of your students. This will help you when you're giving instructions. You can do this with a name game or, more applicable in an art course, ask them to illustrate their names in an artistic way with paper and a writing utensil. That way, you will know their names and their styles.
The basics of art start with lines. First, find an example that you believe shows a creative piece using only lines. Try to find one in black and white so the students can focus more on the lines and not colors. (Color will be taught later.) Show the students what lines are with visual examples, and make them stretch to understand that lines do not have to be boring.
Move through your curriculum with textures, shapes and eventually colors. Show visually how all these elements can by themselves create wonderful works of art. Also show pieces that have combined the elements to make different, but still successful, pieces.
Give homework. Your students may or may not enjoy this part, but it is essential to understanding art. Have them sketch, draft, draw, color, paint or anything else that you feel is important to the day's lesson. Remember your students have other classes, so do not overload them. Assign what is vital to the lesson and move on.
Find local or school-sponsored contests that your students may be able to enter. This will motivate the people who are serious about staying with art, and it will be informative for the students who are taking the class for fun.