Do use their interests! Children's interest are a great way for us to capture a child's attention for a lesson!
Do not be afraid to push the limits! Children are able to do much creatively and with proper guidance and supervision, they can use many materials in a creative way!
Art is by it's nature, a skill of expression. So try not to make it seem like it's “ work ”!
Do your research! Some of the best ideas I have gotten are from hours of research!