No matter whether you try to capture a person or an object, if you need to get the bokeh effect, there is a simple strategy to follow. In this case, you will have to shoot really closer to the subject. This is because of the functionality of the depth of the field.
On the other hand, however, you will get a more distorted effect from the image if you are closer to the subject. With a longer focal length, you will get less perspective distortion. Therefore, you should try a longer focal length when taking portraits of people and avoid unnecessary perspective distortion.