Experimenting with different media, use hatching, lines, stippling etc to create four distinct grades of tone.
Arrange some objects together and do a loose line drawing. Use the above mentioned techniques to to indicate three-dimensionality.
I bought some proper drawing pens as I feel like this sort of technique lends itself to their use. This is something I do a lot of in meetings at work as it helps me concentrate- my notebooks are dotted with cubes throughout. I chose a book for the easiest shape to show grades of colour, then added a small pot of paint for a shape that is simple yet pleasing to depict, then a pencil-sharpener for a bit of detail.
Of course with pen there is no going back! My newly-discovered method of looking at the photo to pick up problems with perspective shows the spine of the book is at the wrong angle. Otherwise I am quite pleased with this simple drawing and the grades of tone I have managed to portray.