User blog comment:Endershot/Sprite requests/@comment-26673567-20150722035919

Tip: Always include a slightly darker outline around sprites. The Super Star and Swag Pet are the ones that need this the most. In the Invisibility Dust or Mystic Chakram, it's beneficial to have an outline that isn't just black, but a darker palette of the sprite's main color.

An exception to the top rule is something like the Eye of Cthulhu or a Man Eater's vines, but the Midas's Eye is sufficiently light to need some darker "tendrils" trailing after it.