These are just sketches and not good enough to me. I am not satisfied which is mostly what eats me. No, I cannot draw, I can only paint and usually on walls (big and I like fresco's) but that's a long time ago. Instead of making sketches at art school I modeled my preliminary studies of the actual project and took photos of them which was allowed and easier for me.

I believe the video you see shows some interesting tricks and it's good for a start but there are some more.

I like the next video... it's his lesson 14. Listen to what he tells and also why is what done.