I was talking with one of my former students the other day about reference. I personally use extremely little reference, as in...when I do portraits...so, very little. I like to train my mind, so if I can't memorize it in a span of about 10 seconds from something I see while walking around, then I'll make it up.
It's something I've been working on since college, creating a mental visual library. Sure, things don't always look right, but it's a lot more fun. A lot of people ask me how I get so much movement in my pieces, it's from watching people and things actually move! If you have to rely on a picture of something in a still moment and don't understand the HOW in the way something moves, it creates a disconnect. You can render it all you want, but it can still be missing that bit of soul necessary to complete a work.
I didn't want to add in any textures or colors on today's piece. I like to shade, just usually don't have enough time, but this is what my pencils look like without any alteration.