You will need:
Paper, 2H, HB, 2B, 4B, and 6B pencils; pencil sharpener, kneaded eraser, ruler (optional)
What you need to do:
1. Outline or visualize a long drawing space in which to shade a graduation.
An ideal size is 2 by 10 in (5.08 by 25.4 cm).
2. Draw a graduation of values from light to medium that extends approximately halfway across your drawing space.
Remember to vary the density of the lines, use different grades of pencils, and vary the pressure you apply to the pencil.
To create smooth transitions, you may need to go back over small sections of some values to make them darker or lighter. You can add additional curved lines in between other lines to darken a value or use your kneaded eraser to dab away sections of a value that is too dark.
3. Continue drawing squirkles closer together and pressing harder with softer pencils until your graduation transitions into darker values.
You should be more than three-quarters of the way across your paper by now, with room remaining on the right to add the darkest values.
4. Continue to the end of your drawing space, drawing the squirkles closer together and pressing a little harder with soft grades of pencils.
But don't press too hard! Remember to let your softest pencils help you achieve values that graduate from dark to almost black.