I don't always stretch my own canvas but over the past few years I have had the opportunity to buy stretcher bars off of other artists at crazy good deals. With an upcoming show I decided to stretch all of those canvases and save some money instead of buying the prestretched canvas.
First of all - let me say that regular sized stapled guns like the one in this video aren't that friendly to smaller sized hands. I basically bruised my palms every dang time I stretched a large canvas. I bought an electric staple gun which saved my hands and allowed for easier manouvering of both the canvas pliers and the staple gun at the same time.
So here is a great little printable PDF and a video from Opus.