Take a good photograph of yourself, preferably something pouty or moody looking. Put the photo on your computer and open it in a photo editing program. I'm using photoshop, but the steps will be the same or similar in other programs.
Desaturate the photo (this means making it black and white).
Open the levels panel and slide both the lightness and darkness sliders in to the middle, so that all of the midtones are made either pure white or pure black. Colour in any areas you wish to hide with black or white.
Crop the photo in to a perfect square, select all and then select "define brush preset". Name your new brush and then save.
Open a new canvas and fill it white. Make a new layer, select a pretty colour, take your new brush and click it once.
Make a new layer and continue until you have a painting you like. Print it or send it to your friends to show off how clever you are.