If you are marketing to an online audience, you may have some work cut out for you. Not only do you risk the piece going for less than you had originally intended.
It is also important to ensure that the buyer knows that they must pay the shipping cost. Older furniture is heavy, and can be costly to ship. You will greatly reduce your profits if you pay the shipping.
There are a lot of websites set up especially for selling older or antique furniture. Choosing one of these sites will ensure that you are marketing to the right crowd.