Sketching is a very important part of my creative process. It helps get the "artistic juices" flowing. Before I sit down to a project I spend a good amount of time drawing thumbnail sketches. These are tiny sketches no bigger than an inch or two. Sometimes I will have a pretty good idea of what I want to create but, I find it extremely helpful to sketch the characters in a variety of different poses and compositions. My friend Will Terry, often teaches that if your painting can not read at thumbnail size go back to the drawing board and fix it.
The nice thing about working at thumbnail size is that you aren't concerned with the minor details. It's more about value and shape and how they relate to each other. When drawing caricatures it's really helpful to work this way because you are focused on the simple shapes that make up the person. I feel that I can usually get a better likeness if I bust out several thumbnails of the person first.
Now I have to come clean with all of you... getting in the habit of drawing thumbnails was a pain in the you know what. Most, if not all, of my college professors and instructors will be the first to tell you that I was not the best at planing out my designs in the thumbnailing stage. A lot of time was wasted fixing compositional problems that could have been solved a lot earlier in the process.
I've included a few thumbnail sketches so that you can see kind of what I'm talking about. I created a scaled thumbnail grid in photoshop and printed them in gray paper. Using an assortment of warm gray markers I can quickly block in my ideas. I still have a ton to learn and look forward to more an more thumbnail drawings!