I admire those who constantly sketch, and especially those who make it look easy. For some, sketching is a part of their daily life. For others, even some great designers, sketching isn't something they depend on to create great work. Either way, every designer should be great at it regardless of whether they choose to use it or not. Sketches are fast, powerful tools of communication, so as a designer when I don't utilize this tool I get frustrated with myself. In an effort to make sketching come more naturally to me, I've committed to start practicing more. I found a great website called idsketching. Check it out if you haven't already. There's some great tutorials, tips, and contests. Here's a tutorial on using contour lines to quickly communicate form. Below are some snapshots of the tutorial.