I think I'm finally gaining some confidence with cups. It's the rims that are the toughest. They're usually rather thin, but not so thin that I can treat them the same as highlights. Also, getting the elipses right is always a major challenge. One thing I talk about in my workshops all the time is how everything is relative, and so to get things "right" you've got to constantly compare everything to everything else: shapes, distances, values, etc. It's really easy to get so focused on one little piece of the composition that we forget to look at the bigger picture. But if one little part doesn't relate to the rest then you're sunk! I have 2 main tricks for making myself look at the bigger picture all throughout the painting: squint, and back up.
