The smaller number of breeds that you try to work with, the better success you will have. Master one breed before you add the next one.
Start with the very best birds that you can afford.
Go to shows. Present well raised, well fit birds.
Be friendly. Be a good sport. Always keep your word. Be honest. Reputation is everything.
If you start to win consistently, if you have good birds, if you have a reputation that you can be trusted, you will sell birds, and get a decent price for them.