this is the diagram of an online bookstore I made.

There are some simple business rules applied:
Customer can order many products(Items).
An Item is considered book, cd, dvd, e-book,...
Customer can have many addresses.
Item can have one author ( for now, i will maybe expand this to many authors, which is logical i think), one publisher and many translators.
Also, the item can be in many categories.

I think it's all in 3NF, maybe there could be problem in the Customer table with the email and username attribute.

The real problem is in the entities and their relations. I have two problems. I dont know if the ordering process is connected right, and the customer's payment methods (consider that there are not all attributes in the payment method table for now).

Any ideas or corrections? Advices?

Thanks, Matic