Edges matter
I'd heard the term "edge control" before but never really understood it until seeing Mark Westermoe demonstrate it. He explained that one thing that can separate a good drawing from a bad one are well designed edges. He went on to say that when making a drawing "you must be conscious of your choices for the transitions between your lights and darks. - the lights and shadows. You must consciously "design" your edges to make an interesting picture. You're not copying reality (your model or reference). You are designing a head (or figure, or a picture, etc.)" I'll admit that I've never given much thought to this before now and will pay more attention moving forward. Here's a quick doodle I made to remind myself about edges.