https://www.craftsy.com/class/sketching-for-concept-art/

Bring unique characters and environments out of your imagination and onto the page with concept artist Donald Yatomi. Generate thumbnail character silhouettes, refine them with rules of proportion, and turn your favorite into a full-size sketch. Use your sketch, along with reference photos and professional tips, to create a final blue-line drawing. Next, create environment thumbnails. Employ a horizon line, vanishing points, and a ground plane as you transform a thumbnail into a sketch that’s drawn with accurate perspective. Build a sense of mood with strategic details before Donald guides you through the creation of your final blue-line drawing. Hone your characters and environments until they’re ready to be handed into an art director, used in your own projects, or displayed proudly in your home.