The pure act of representional drawing (drawing what you see, "copying it") needs just two basic actions: measuring and comparing.

For that, you have to teach yourself how to see things in the most objective way possible, without meaning. Don't see a dog or a head or a leg, but just a mass of shapes, lines, areas. Measure them, compare them. It's all about that.

People think drawing is in the hand, but it is in the eyes and in learning how to see things differently.

Good luck! It can be very therapeutic and rewarding.