The place to start the implementation is to list exactly what the user will do to achieve his or her goals and how the system will respond to each user action.
A well-designed and humane interface does not need to be split into beginner and expert subsystems.
Because starting with copy focuses you on the customer and the dream product you’re creating for them. You’re not worried about which font you should use, the border radius on your dialogs, or the interaction convention of the week.
“ As far as the customer is concerned, the interface is the product.”