For promotion, You can make a broadcast message and send it to watsapp groups, social media such as facebook, insta etc. You can buy artificial jewerally to wholesaler shop, in every city there are so many wholesalers markets or you can ask somebody in your friends or relatives whose has same business or you can find it too on Facebook or Instagram, mostly people is doing their business through online. As concerns for terms and conditions You should hire a contract lawyer to draft a set of standards terms and conditions which you will in future.