To determine where values change when light moves over an uneven surface by using a range of values to paint the different values in a realistic, monochromatic self-portrait;
To effectively communicate an image that looks like you through careful examination of the values and structure of your face.
If you want to create a value self-portrait there are many skills you need to have. While you are looking at your picture you need to find out which areas are dark and light and what value they should have. While painting you need to mix your paints well and have a good tectonic for painting. When painting you have to make sure not to leave any gaps between the paints.