Make sure you ask for references, and by all means call them. Check out the environment the dogs/puppies are living in. Is there ample room and is it relatively clean safe and free of feces.
Ask the breeder how many litters they usually have per calendar year. A lower number usually is better, it generally shows more care is given. I hope some of theses pointers will help in determining the correct breeder.
Top Oregon Boxer Breeders