The Swedish watercolor guru Arne Isacsson (1917-2010) said: "Don't follow recipes!", and many of his learners like to quote him. In my opinion this advice might actually discourage some inexperienced students. You can certainly learn a lot from following a painting recipe (as long as it's not the only thing you do), because it gives you the tools you need to eventually go your own way. That might be part of why the most innovative watercolor painting is developing in China, where copying is an important part of learning. Here is a two-step illustration of how to use shadows for shapes.