Go to a hillside, shore or wooded area nearby where rocks are plentiful. Examine the rock shapes around you. Look for large and small rocks. Examine the texture, size, curves and lines of the rocks around you.
Take out your sketchbook. Sketch the rocks that you find most appealing in shape and texture. Record your observations in note form beneath each sketch. If the rocks remind you of other forms (natural or man-made), write down these forms beneath the drawing as well.
Return to the actual rocks. Choose a large rock as your base and place it securely on a flat spot of ground. Gather together the other rocks that you sketched and that appealed to you.
Place one of these rocks on top of the large, base rock. If this rock does not seem right, try out other rocks in its place to see which is most pleasing compositionally. Make sure that the rock is secure on top of the base rock as well as visually pleasing so that your creation does not fall apart.
Place additional rocks next to or on top of those you have arranged so far. Rocks are move-able, so revising your sculpture is not impossible. Make sure that they are balanced and will hold. When you have an arrangement you are happy with, sketch the sculpture in your book and write the date, location and types of rocks you used beneath it. Review your sketches at home and make notes for possible future sculptures, types of rock, etc. Keep this sketchbook with you at all times while you are learning to work in this medium.