Sometimes no matter how hard you try in camera to achieve the perfect image their some things you can control. Maybe it’s a car in the background, maybe your model had a hair tie around their wrist. The hair tie!!! There are ways in Photoshop to easily remove those objects.
You can use the clone stamp and content aware to help you. I usually use a combination of the two to get the most natural results.
You can view this quick video here on how to use these tools in Photoshop to remove distracting objects: