Hi Mic, take it easy. If the assignment is to shoot portrait of your father, you can do few things:
- shoot a portrait that shows your father’s profession. So include some elements that can tell what his job is
- shoot a portrait of him doing his hobby
- if he has great smile to show off, take a portrait of him while he is smiling
- you can always take a traditional portrait of your father. Position him at a slight angle from the camera. Position him near the window to have good natural light. Make sure the background is not messy and is not distracting. You can shoot either full body, half body, or just a head shot.

But most importantly, understand the theme of the assignment first in case there is specific message that they want to show in the photograph. Hope this helps.