Well you need to set up a goal and then select breeds that will help you achieve what you want. Im creating one called Scottish Hens (I live in Scotland ct) and I want something sustainable that is feed efficient, brood chicks, males protective over hens so they can be free ranged, cold hardy and still lay through the winter. With that goal im selecting breeds to create that. I have a few rules too, such as Only the first generation can be from pure parents, the rest must be cross breds and I can't import eggs from another state. So im only working with birds from the ma/ri/ct/tristate area. From there is Cull Cull Cull Cull and more Culling.
Now to actually get the breed recognized, well that's a whole entire different story!