Using anything from a 2B to a 6B to draw a piece of fruit...halve, quarter or cut slices and arrange them to make interesting shapes. Shed some light on the still life so you have good contrasts and shadows.
Draw using line only, do not add shading. Vary the pressure you put on your pencil according to how dark the edges are or how much they contrast with the background. Include lines, shapes and markings you see on the skin and inside the fruit, not just the outline. Finally draw round the shapes of the shadows lightly where they are soft and press harder where they are strong.