We are going to make photorealistic push pin portraits.
We will be guided in our pin placement by a low resolution indexed color gif image we will create in Photoshop. The .gif will use a limited palette restricted only to those colors in which the plastic push pins come.
This tutorial assumes you have some access to and basic understanding of Adobe Photoshop.
Using Photoshop, adjust your image so that it contains a nice range of colors and values, with no large areas of pure black or white or any other color. This will give you a dappled variety of push pin colors across the finished artwork, rather than large, boring expanses of a single hue.
I'm using a photo I took of a woman who sells her hats and headdresses on the internet.