Ken McMillan once told me that whenever you can find an object from your own life that the character you are portraying can use, then it will help you in two ways: it will help you stay connected to who you are (one way to overcome nerves) and at the same time it will help you become the character because you and the character have "something in common."
What's even better is when you can find something in the play... a reference, a piece of business, an article of clothing... something referred to in the play that you can connect with that personal object.
I became the owner of a plant when a dear friend died a couple of years ago. Her name was Sybil Trubin. Early in her career she had produced at the Cherry Lane Theater in New York. We would sit and talk "shop" for hours... I think of her often through this process and I am even sorrier she will not physically be here to see this play. But I have decided to make her plant a part of the set. And I am going to make it an active player (something for all those people who are coming to the play to be on the lookout for). The plant connects me to her, to Ken, to myself, and to the play. I miss you Syb.