I provide the reference photo by Terricks Noah in the resource section. This is a copyright free image that you can use in your art. 

I will show you a technique to make an accurate sketch, drawing from large to small shapes. As we are working digitally, we'll be able to check the accuracy of our sketch and fix our mistakes. This is a good way to learn how to sketch a portrait, looking at our own mistakes.

If needed, I provide my own sketch so you can easily jump in the color part, unless you prefer tracing over the photo.

Then the fun part: adding layers of colors, playing with different hues, blending modes, transparencies, to achieve a rich and complex portrait, featuring all shadows and highlights of the face. I provide my palette as well, if you need a basis to work from.