Final answer:
Crystal should inform the customer about the check policy, verify identity with ID, check check details, get two phone numbers, initial the check, and call the manager for approval.
Step-by-step explanation:
When Crystal, the head cashier, needs to explain the procedure for approving a customer check over $300, she should include the following steps: Firstly, inform the customer about store policy regarding check payments. Secondly, verify the identity of the customer by checking a photo ID to prevent fraud. Thirdly, ensure that the information on the check is correct, including the date, amount, and signature. Fourthly, obtain two organization phone numbers from the customer for additional verification if needed. Fifthly, the cashier should write their initials on the check to indicate that they have processed it. Lastly, call the manager to provide approval for the check before the transaction is completed. This process helps to maintain the integrity of the payment process and minimizes the risk of accepting fraudulent checks or incurring overdraft fees on the store's account.