After some fiddling / experimenting with creating a Ruby-on-Rails (with a PostgreSQL database) that is testable locally on a mac, and also deployable remotely on Heroku, I thought it might be wise to jot down some notes just in case I forget how to repeat this again!
(Note: I'm not a pro in Ruby/Rails/Postgres just yet - this post is meant to be for my own "rescuing" purposes. I'd recommend you use the official Heroku Getting started with Ruby / Rails tutorial to begin with. Use this post only for additional info / resolving issues when you get stuck. I've included some handy links below).
# Useful Tutorials and Articles
Some really important tutorials / articles - highly recommend to use these frequently:
On installing Ruby, Rails, rbenv