While we're clearly obsessed with learning everything about beauty, we'll be the first to admit that the sheer volume of information can be daunting. And some important tips can get lost along the way. Are you using the right primer? Are you using bronzer correctly? And is powder really necessary? It's easy to make some big makeup mistakes without even realizing it. Well, that stops now. Once you see which mistakes you've been making, you'll swear to never make them again — after all, your beauty reputation is on the line. And don't think that only beauty newbies are prone to errors! So read on: even if you're a professional, you're bound to pick up a new trick or two.