A classic exercise for developing the eye-hand connection, improving observation and freeing up your line, Blind Contour Drawing is often learnt as a student and then forgotten about. If you haven't done one lately, why not give it another try. You can make it more challenging by choosing an interesting and complex object. Beginners might like to try the example in this blind contour drawing tutorial to start off with, which explains how to do a blind contour drawing, and includes several different examples.