I think the biggest problem people have when drawing with crayons is that they regress to being five years old again. They hold the crayon like they're coloring again, instead of applying it like a fine art medium. Another problem is that many people want to make it perform like colored pencils. While similar in application, they are quite different. You should not use crayons and expect them to behave like colored pencils. You'll be setting yourself up for disappointment.
Colored Pencils is one of the easiest media to handle since they're pencils and you can control your strokes well. There are also a lot of available colors to choose from. First, cover the entire drawing with light strokes. Then, you can proceed with the thick lines to add texture and effect to your drawing. You can also add some more details in your drawing like this one. Soft pastel was used for the blue shadow_effect.