A quick spelling check goes a long way.
Review each name, size, colour and number of identical sets before checkout. To change a personalised name or colour, remove the old line and personalise it again; changing quantity alone does not change its spelling or style.
Delivery is separate from the product subtotal and shown in the cart/checkout for an Australian address. Test checkout takes no payment and creates no physical fulfilment commitment. Understand delivery and returns before submitting, and keep the confirmation number rather than expecting a test email.