Welcome, Andres,
You ask a very common question; here's what I would suggest beyond the usual RailsTutorial, Agile Web Dev in RoR, and Rails 4 in Action books.
First, Joe's suggestion to join an existing project is a very good one. It's easier said than done, of course, there aren't many that just spring to mind, but there's a few:
1. Rails, itself; learning how Rails works and contributing to its development will teach a lot
Other books that may help:
1. POODR (Sandi Metz)
2. Eloquent Ruby (Ross Olsen)
3. The Well-Grounded Rubyist (David Black)
4. Practicing Rails (Justin Weiss)
Ante up the $9 and watch all you can of RailsCasts, even though many are old, the concepts are still invaluable.
Head over to Avdi Grimm's RubyTapas site and sign up; Avdi is offering some great deals on some coproductions with others, as well as a his own great set of small plates of ruby wisdom.
Learn more about Database design; Date's books on understanding relational calculus are quite helpful, but very expensive since they're university textbooks. I hope someone has some good suggestions here.
Learn about the frontend design enough to be able to talk to frontend developers and designers. It's a language we all need to share.
Find a local Rails / Ruby user group, meetup, etc. Get involved in the local development community.
And practice, practice, practice. Create toy apps, learn about N+1 problems, using state machines / workflow processes, form objects, service objects, background jobs, accessing other web services / APIs, writing APIs, debugging your applications, deploying Rails applications in various environments, ....
so much to learn
Tamara