I just recently started drawing again, or maybe I should say sketching because that is basically what I do. When I started I tried it out by myself, trying to remember how I did many years ago, and I realized that they turned out pretty well but I didn’t give it much chance, I never tried to redo parts of the work just finish it up and try it again. But that is a strange approach to me, I usually don’t do it that way when coding on projects, then I usually start with something “sketchy” unfinished in a whole but with distinct parts that works but that probably will be refactored when I have more knowledge of the final solution. Basically when the overall “sketch” (prototype) is finished and I want to improve details.
This is how I should have done when sketching as well, there is no need to improve lips, eyes, ears and such before you get the overall dimensions of your sketch into place. A painter probably doesn’t finish small parts of his painting before the overall sketch is in place.
So when starting with any project, ask yourself: “How can do this iteratively?” if there is a possibility to use an iterative approach to your project, then use it.