Payment: what to confirm before payment
Before payment, please confirm the payment method and payment terms. That confirmation should cover the accepted methods, the payment schedule, and any deposit or balance arrangement for the order. A payment schedule that is clear before payment prevents the most common payment dispute, which is a disagreement about when each part of the price falls due.
The source service pages mention payment methods in a frequently asked questions section, but this site does not repeat those methods as current order terms, because the questions section does not establish that those methods are the current terms for a new order. A buyer should ask for the methods and terms that apply to the order in question, and get them in writing.
Shipping: what to confirm in your inquiry
In your inquiry, please confirm the shipping method. The shipping method should be chosen with the destination, the quantity and the delivery date in mind, and it should be confirmed together with the lead time, because the two together determine when caps actually arrive. A shipping method quoted without a delivery date is incomplete.
Also ask who arranges shipping, what the shipping cost covers, and what happens if a shipment is delayed or damaged. Those points are routine, but they are also the points most often left open until a problem occurs. Raising them in the inquiry costs nothing and prevents a dispute later.
Keeping the commercial record
Keep the written confirmations of payment method, payment schedule, shipping method and delivery date with the order record, together with the quantity, sample and timing confirmations. For a custom cap order, those written confirmations are the commercial terms, and they should be checked against the invoice before payment is made.
If an invoice differs from a written confirmation, raise the difference before paying rather than after. A payment made against an incorrect invoice is harder to correct than an invoice corrected before payment.