The most typical light source for taking photographs is the sun. Whether outside or inside by a window, the sun is the most extreme version of single point lighting. Professional photographers working outside often use large white or silver reflectors to "bounce" light on their subject in order to soften the shadows.
If you are inside by a window, and that is your light source, it will improve your pictures if you use a reflector to bounce light to the darker side of the object.
A very basic example is demonstrated here where the top photo shows Sasha with light coming from one side. The face is illuminated on one side but quite dark on the other. This is dramatic but not very flattering. The middle picture shows the result of using a white board placed close to the doll but out of the picture focus range. Now the face is illuminated on both sides with one side still in shadow but more softly illuminated.
The bottom photo shows how close the white board is to the doll. Typically, bounce boards are either white or silver. A mirror will reflect almost 100% of the light source while a white or silver board will reflect about 50% of the original source -- creating a softer shadow side to the face.
This technique works both inside and outside. It is always best to avoid photographing a doll in direct, intense sunlight as it tends to create very deep dark shadows. These can be softened with a bounce board but you will get even more beautiful results if you work in a slightly shadowed area on the fringe of direct sunlight or on slightly cloudy days. Or, you can take photos late in the afternoon when the sun is not as strong or directly overhead.