1. Cross hatching
With cross hatching you are drawing parallel lines, varying the direction of the lines and layering them to obtain different intensity of shading.
2. Hatching with parallel lines
Hatching with parallel lines is the same as cross hatching, except you are making all the lines go in the same direction. It is a bit more time consuming than cross hatching but can lead to interesting results.
3. Contour lines
Contour lines can be done in many different ways but basically the idea is to have the lines follow the shape of what you are drawing.
4. Scribbles
Scribbling is a fun way to shade a drawing and it goes fast!
Scribble drawings shading works particularly well for portraits and still life.