I think i’m absolutely clueless?

I’ve been playing this game for quite a few years, but after going through this subreddit i’ve came to learn i’m absolutely terrible at the game and know nothing about what i should be doing to maximise playing it?

Every time a new restaurant is unlocked i immediately open it and move forward, but with the most recent ones i’ve unlocked, i haven’t been completely upgrading the restaurants like i did for most of the first restaurants. I’ve never had more than 100 rubies at a time, but i’ve seen people suggest to save hundreds before moving to a new restaurant which feels absolutely impossible to me.

I don’t put money into the game unless i absolutely need or want something so this isn’t really an option for me. I have no idea what i’m doing 🫡

edit - spelling :)