Shading your work can transform your artwork to have more depth, value and when done correctly, can make your drawings appear three dimensional.
Hatch shading is done by applying multiple lines in varying pressure and number. As shown below we have a lemon that has been hatch shaded, where the shadows are most intense we not only see darker lines but more of them. Also notice how the lines follow the same general direction.
Similar to hatching, cross-hatching is the simple addition of adding a few lines running in the opposite direction to the ones you lay down first.
This method of shading can be hard on the wrist, stippling is shading through a build up of dots. the more dots applied the darker of the shade you'll get. This kind of shading is also great for adding texture.
To blend your shading is quite easy, starting first with laying down your values then using a blending stomp to blend your shades together. Eventually you will get a smooth gradient.
Random Line shading is a loose application of crossing lines. Very free form!
These are just a few techniques you can use, feel free to combine, experiment and try something new!