A good portrait is an image of a person that manages to tell a story. A good portrait evokes emotion. Composition is a combination of the scene on the ground and the scene within your head. For portraits people choose to have high angles in order to also capture stuff in the background. You can add the composition to add balance to the entire frame. A good portrait also should have potential visual story telling. In some cases you can make the background much more dominant. Soft natural light is also good in portraits. In the portraits having story telling is good because in some cases pictures could look sad. Also there should be space in the picture so there is more to look at.