A tip from a classic guitar player. NEVER look at your hands, except when playing a VERY complicated section, to make sure the hands are in the right position. Also, NEVER look at the audience. It's distracting. Either stare into space or close your eyes. You need something nondescript to stare at while playing, so you can keep your concentration. When practising, I stare at a piece of blank paper to help me keep concentration.