Please forgive me if this sounds overly simplistic. Since I don't know what you know already, I'm going to assume the least ---
Also, to be fair, I'll tell you I've been raising chickens for eggs, not show and am just getting into breeding myself; HOWEVER, I grew up with parents who bred/raised Boston Terriers (dogs), bred and showed dogs myself and now breed Netherland Dwarf and Rhinelander (rare breed) rabbits for show so I am familiar with breeding to a standard in general.
As others have said, the BEST way to start is to attend shows and find a breeder willing to show you what good type looks like and has stock/eggs available for you to purchase. Keep in mind even in this best case, you won't be getting the top stock because the breeder is keeping that for his own breeding program.
As it sounds, you already know the reality is that not everyone has such a resource nearby so the alternate is time consuming but rewarding. Start with learning the standard for your chosen breed and get a good handle on genetics. The latter is particularly important if you are working with a color breed like Slate turkeys. You can't get where you want to go if you have no idea where that is (standard) or how to get there (genetics.)
The positive thing about hatcheries is that they have to be pullorum inspected/certified to sell birds interstate - not every local breeder is. Birds are required to be pullorum free (and prove it) in order to show.
I hope I'm not violating board rules by telling you I've used McMurray Hatchery for years and like the birds and service they've provided. Others do not like them. Many of their birds are not show quality, but you can end up with some that are. This is where knowing your standard comes in. Select the best to breed, cull hard and keep moving forward toward your ideal. Once you start showing, you will get to know the other breeders and can improve your stock with people you trust, but this route is going to take time - think years not months.
Good luck!
