The light coming from a window has the advantage of being a very bright source ; what you see is the result you will directly get after shooting. The different light patterns are only a few steps away from the more sophisticated settings. With lighting from a window, you have to move around or change where your model will stand, to create the desired light pattern.
Keep in mind that the closer your model is to the window, the softer the light will be. Curtains will also add softness. As a result, it will give very uniform lighting, which is great for showing all the details of a face with tiny apparent shadows. However, if you place your subject at a considerable distance from the window, you will get both longer and darker shadows. Soft light is, in my opinion, better for portraits. It all depends on the style you are looking for. I photographed these three images with natural light coming from a single window. In each case, the light shape was my first consideration. In other instances, I sometimes use reflectors to control contrast, fill in shadows. For the last one, I also used artificial lights (ceiling light and flashes) to get a more attractive background.