There are several lighting positions that photographers have developed over the years. People like George Hurrell, who used tungsten to shoot stars, used these lighting positions. Learn to identify what a butterfly or Rembrandt light is. Knowing these positions, and where the light placed to create them, will help you see how photographers light their images. These are departure points from which you will create your own look and direction. It’s hard to depart from someplace you have never been there. This will teach you the basics and give you a good foundation to build on.
This video is not as slick as some of the others they have done, but it has great basic instructions on portrait lighting. (Don’t miss the ending its the most exciting part!)