Only ship after eBay confirms the payment in your Seller Hub - do not rely on emails for that - check your own eBay account first. Are you fully enrolled in Managed Payments to receive buyer payments?
You're a new seller and will be targeted by scammers - do not respond to any requests to text or email a buyer.
For that book, once the payment is confirmed by eBay, you must add Signature Confirmation to your label as the order is >$750. Also consider adding Insurance in case of loss or damage in shipping - your shipping $estimate is not enough for either.
