This is a great synopsis on how pixel art has evolved through the years and continues to make waves in Gaming.
I have always wanted to learn how to do it and i have found a valuable program called Piskel that allows you to create sprites for free.
You can download the program here: http://www.piskelapp.com/
here is also a tutorial to help you get started. https://www.youtube.com/watch?v=tlpCU871Xyg