First of all, you should review the qualifications of your suppliers. If purchased from a production enterprise, the production license, product registration certificate, sample label of inspection report of registration form, business license, organization certificate and tax registration certificate shall be examined. If you buy from a commercial enterprise, you only need to review the supplier's license and collect the registration certificate if necessary.
If the supplier is qualified and legal, you can ask him to purchase goods. There should be a formal delivery note, invoice, contract and quality assurance agreement when purchasing. There are provisions for after-sales maintenance in the contract, and each batch of goods is accompanied by the factory inspection report of the batch of products, and the whole box packaging has a certificate of approval.