It's not a crazy question, but I haven't seen a tutorial. I have decorated a few by looking at pictures of the decorated ones. Mine turned out pretty well.
Here is what I did. I used copy paper to make a pattern.
Measure the width of your binder clip. Cut a strip of paper that width and longer than you need. Put the paper on the clip, wrap around to the other side and mark it. Use this for your pattern to cut your cardstock. I used pattern paper.
I adhered my paper with glue dots on one side, put another glue dot on the bottom of the binder, and then on around to the other side, fastening with a couple more glue dots.
I decorated the metal "arms" with ribbon knots. Here is a great picture of some cute ones in the gallery:
Binder Clips by Joeknee at Splitcoaststampers