Let's face it -- we all make the occasional makeup mistake. When you're a makeup artist to the stars like Billy B, however, you've seen it all, which is why were dying to find out the absolute worst beauty mistakes he's ever seen.

"You can teach someone technique all day long. It's a formula. But you cannot teach them the art of makeup. You can't teach someone who knows how to dress, but you can't teach them style. You have to have a sense of that," Billy told us. The root of it, according to Billy, is that some are just better at makeup than others, but that doesn't mean there's no hope for the makeup-challenged.

What's the one mistake Billy says is easy to avoid? "I always notice when someone is wearing too much foundation and concealer. It's a trend Kim Kardashian is sort of responsible for -- a lot of girls love her approach to a full face. She's a beautiful girl and she doesn't need that much makeup on her skin. The goal is to really take care of your skin and let people see it," Billy says. Whether you are looking for a fresh face or a done up look, follow Billy's advice and avoid caking on the foundation!