Write a clear specification before you ask for a quote: exact dimensions, materials, colours, packaging, labelling and any certification you need, not just a product name. Vague requests produce vague quotes that are hard to compare and easy for a supplier to reinterpret later in their favour.
Always order a paid sample before committing to a bulk order, even from a supplier who looks reputable. Compare the sample against your specification in writing, and keep it; it is your reference point if the bulk shipment later fails to match.