This handout reminds students what they should always do before turning in their work. Always simplify, label, use correct notation & terminology, etc. It is a colorful page that I have my students keep in the front of their notebook so they remember that they will lose points on assignments for not following these rules.
This also works well uploaded for online use where students can access it. It certainly helped me with those "why did you take off points?" questions!

I have several of these that are geared to different areas of mathematics.