Well who do you call, who do you send it to john? Plus what do you recommend doing to put on a resume besides playing in a league, certain tournaments, certain things...?
How do you know what different sponsors require? Is there like a list?
Win a couple big tourneys in a higher div. Get noticed and talk to Tourney Directors. Ask them questions. It's not impossible, just tough to do. A sponsor doesn't have to be a "Redbull" or "Innova", try out a local sponsor first to get your feet wet.
Pretty much what John said. Do more for DG than just playing it.
Who do you want to sponsor you? Check their website for contact info. Some disc manufacturers might be looking for more players, some won't. There are a few retailers who sponsor disc golfers, you need to check locally, or get to know one of them. Ask players who you know are sponsored if their sponsors are interested in adding to their team ... sometimes a reference can help.
Good tournament results, good PDGA rating (showing improvement, or consistency), commitment to play, what you do and where you play. Working at a tournament as a TD or volunteer, helping maintain a course, contributions to the disc golf community like workshops, or disc golf events.
There was a good article in Disc Golf World News a year or two ago [about what disc manufacturers look for in a sponsored player]. I'll take a look at my archive and see what issue it was specifically.
Beside being a good player (you don't have to be the best), most sponsors are looking for players that will best represent/help their business, are committed to the sport, contribute to the sport in other ways besides playing well, and project a good image.