Where to start developing SPA applications?

Question

React

I decided all the same to start making an application for a diploma (Service for ordering food, most likely pizza, etc.).
Stack: JS / react / redux / redux-saga / firebase (db + authorization)
Tell me how to design an application and where to start development?
It seems like it’s not the most difficult project, but I’m sitting and I don’t know which side to approach.
Perhaps there are some tips or well-established actions for designing and developing applications