Amazon's login and registration screen is the standard by which other login screens are measured. The simple flow consists of: 1) entering your email address, and 2) entering your password. If you are a new customer, simply select the new customer radio and the follow up screens provide the registration flow.

1. Enter your email address, if you're not registered, select "New customer," otherwise log in
2. Enter registration info

https://amazon.com/gp/sign-in.html