Lately I've taken up a daily sketching habit with charcoal. Why charcoal? Sketching with charcoal is quick, simple and inexpensive. Charcoal makes it easy to put down a wide range of tones and build a complete composition. Not a lot of tools and materials are required. Here is my charcoal sketching tool tray.
You don't need everything you see in this photo. You can start with this basic list:
Paper (something with some tooth)
I like to sketch at the easel, I just prop up a large sketchbook and sketch vertically. This forces me to sketch more loose from the shoulder rather than from the wrist. I keep these sketches to 10-15 minutes each. They are not meant to be finished works but rather practice and composition tests. I do one or two of them first thing every morning.
As you see here I am sketching on a large sketch pad even though each sketch only uses part of the paper. Here are some examples of sketches I done lately.