When using a cover and back, place a sheet of paper in between before punching.
GBC Binding Machines
come in many different models that are suitable for low volume home use, right up to very high volume departmental use. You only get one chance to make a first impression so make sure you use a GBC Binding Machine
to bind your next report or proposal for a sharper and more impressive look than ever before. GBC have produced a handy Binding Guide that can be downloaded here