Put out the best quality you are able to put out. If you do not have a good microphone but have a little web designing skill and impressive writing skills, start up a sports blog. If you have an adequate microphone but are unable to put a set together, run an audio-only podcast. If you have the resources to run your own moderately impressive video show, however, aim to do that.
Focus your sports show or blog on the aspect of the field you are most interested in. If play-by-play announcements are your thing, do play-by-play recaps. If commentary is more your style, however, include plenty of that.
Take your digital presence into the real world. Offer to cover local community sporting events on your blog or podcast, or even offer to call plays in person when applicable. Interview community athletes and those involved in local athletic programs.