Lots of ways to tackle selling your photos. If you're trying to sell action shots, it's a flooded market so the shots need to be killer and showcase something specific and of course be an athlete someone cares about. Aside from actually being contacted for specific shoots, the best way to sell to mags and websites is just by emailing them photos they may be interested in.
I've never gone the stock photo route. But, it could be a decent way to have a few extra bucks...
Unless you're a well knows photographer, selling prints and actually making a good return on them is rare.