Here are a few ideas for customizing your stockings!
The easiest thing to do is to glue or sew on some decorations. Your local craft store or superstore has lots of cute things in the Christmas section. The snowman on the stocking to the right is an ornament that was stitched on with sewing thread.
You can also sew or glue on felt cutouts.
The striped stocking below has little xmas light charms sewn on the rolled edge.