A big mistake made by many photographers old and new is to place their photos with agencies without the approval of the subjects in the photo.
And that means people in the image and from the person responcible for any building or object that may be in your image aswell.
Make sure that you have a signed model/building release form.
This is a vital step in trying to avoid litigation, which can be a very expensive and unpleasant experience. Unfortunately the rules are different state to state and country to country and I would strongly advise seeking local advice.