参考

Active Record Nested Attributes
accepts_nested_attributes_forの簡単なまとめ
has_one関連でaccepts_nested_attributes_for / fields_forを使う
Railsのユーザ認証deviseを用いた簡単かつ突っ込んだ実装
Writing to a second model when using Devise

• stackoverflow

Profile model for Devise users? -これが一番わかり易かった。
Create a user profile upon registration add profile form fields to devise registrations#new form
How to add a UserProfile to a User when user signs up? (Devise, Rails 3)
No output through fields_for when using a one to one relationship
How to get devise to work with accepts_nested_attributes_for in a has one relationship?
How do I use nested attributes with the devise model
関連：
OmniAuth + Device で認証する①
OmniAuth + Device で認証する②