Have a Backup Payment Plan Ready
This is extremely important.
When you go to buy your iPhone 7 you'll want to have a backup payment option in place in case the card you use gets flagged by your bank or credit card company. This has happened to us and many others in the past and it could happen to you.
If you don't normally make purchases at Apple or if you usually don't make big purchases on the card you're using to order, the company responsible for your card might flag the purchase. In turn, this could prevent you from putting in an iPhone 7 order.
If you have another credit card, make sure you have it and the information associated with it handy. It could prevent more than a few headaches.