Explore your taste. Before diving in and making a purchase, spend some time getting to know what sort of work you respond to. Make weekend dates to browse local art museums and galleries, pick up an art magazine or flip through a stack of art books.
Are there certain styles, colors or subjects that draw you in? Do you gravitate toward black and white photography, modern abstract paintings, still lifes? Note what you love. Exploring and observing will build confidence, not to mention expose you to new styles and artists you might never have found otherwise.