What to do in a lift when faced with a stranger?

What does one do when you're in the lift with a stranger (i.e. just 2 of you) and stood just facing each other and your eyes happen to meet? It felt pretty awkward and the only thing I could do was try to smile and try to appear that you're not staring. But then you will not know if the person will smile back or will think you're strange. Should you hold your gaze or quickly look away? Ah well.