One way to use a prop in theatre is to treat the prop as though it is another character. If a gentleman has left his briefcase behind, the lady on stage might stomp on it if she is mad at him or caress it if she is in love with him. This is particularly useful if she is alone on stage, as it provides another "character" for her to address her lines to.
Do you have any moments when a character seems to be talking to himself? Can you use a prop to ground this conversation? (Remember, writers can use "props" too. Just write in an object for your character to manipulate.)
How do your characters treat each others' belongings? Does a daughter hold her mother's hairbrush with care, almost reverence? Does one friend treat another's belongings too casually? Develop these moments so that they are appropriate to the relationships involved.