Either, at first, place orders at an ODM factory (produced from the bar) and finally come up with your ideas and designs after working with them for a while, or hire a sourcing agent who can help you get in touch with trusted factories. Start as low as possible, as long as the number is useful to the provider. At the end of the day, they will only respect an exclusivity contract if they see that it is useful to them. Be sure to sign the exclusivity agreement with the company that is the owner of the actual IP, not with a mailbox company that has nothing but a USD bank account. And don`t forget to create the chord in English and Chinese, if it`s not feasible, at least have the subtleties translated into Chinese. A standard NDA protects trade secrets from disclosure to the public.