Complex relationships in Ruby - display data across many tables


I have designed an application consisting of 20+ tables, and utilizing
Ruby on Rails.
I am using an authentication system for users to login. I want to
display to the user, when he logs in, information related to him that
can be found across many tables, between these tables there are all
the possible relationships. How can I accomplish this in RoR? Should I
consider using views, multiple joins? I did not managed to get
information from one model further than 2 tables looking in the tables
design using classical approaches like “has many”, “:through” etc.

Can you please share your knowledge?