Good question! When I worked at the Rails shop, we had a standard Gemfile which we started with. It had way too many things in it. Some of the absolute requirements would be to start with 'better_errors', 'letter_opener', 'haml-rails', 'simple_form', 'devise', 'cancancan', and (probably controversial, but my favorite) 'cocoon' (i.e., the thing that makes nested models take so little code). You can probably throw in twitter-bootstrap too, but...

Also, I'm still using RVM. I never made "the switch" to rbenv; I never saw the problem with RVM.

MySQL vs PostgreSQL doesn't matter to me. I've done a lot of both. And Oracle. And SQL Server. I've never seen a problem with using any database with ActiveRecord.

Starting a new project, I just install the latest, stable Ruby, install the bundler gem, then grab the latest, stable Rails, add the basic gems, bundle, and start letting rails generate the basics.

I'm bootstrapping my projects with Vue support, because I think that's the JS framework that fits most-nicely in Rails, and there's always a presentation-heavy page that needs that kind of treatment.

(I'm assuming a Mac or Linux here. I've done this on Windows for a time, but WSL has changed the game there, and I've not actually tried to use it in anger.)

Just read through https://guides.rubyonrails.org/ Unlike the sibling comment I suggest staying away from additional gems as much as possible especially if you're a beginner. Do things the officially blessed Rails way and you will run into the least amount of problems. All gems that try to 'fix' something in Rails will often have downsides of their own and can cause hard to debug issues in corner cases.

I can see where you're coming from, but I wouldn't advise rolling your own authentication and/or authorization systems, especially as a noob.

I still don't understand why there isn't a Rails' way for authentication and/or authorization systems.

Started a greenfields project a few months ago. Decided to go with Rails API and Angular.

I've found https://github.com/markets/awesome-ruby a really good resource.

One thing I feel stands out is the graphQL gem. It has an unpolished feel...but dang graphql+active record is a killer combo for rapid development!