If the plant was purchased in a pot, then it is probably already in a quality potting soil and requires little more than watering and grooming for a while.
If potting a flowering plant to bring indoors or to give as a gift plant, start with a good quality, commercial potting soil. These are usually lighter in weight than topsoil, sterile and pest-free. Many are available with a mild starter fertilizer in the mix.
Select a container with a drainage hole or be prepared to drill holes for drainage if there are none.