What are your stages when creating a web app as a full stack developer?

Recently I've asked some questions here regarding ReactJS , boilerplates, CSS etc.

I realized my hardest problem when trying to create complete ReactJS apps is organizing and deciding development order. Maybe I lack order as a person, or maybe it is just my ADHD.. How do you guys plan or structure a project when firstly thinking about a complete target or purpose.

As in:

• Do you style and write css aesthetics while creating components? Or maybe you write layout first and then add styles?
• Do you integrate Redux from the first moment before having components written?
• Do you write backend endpoints when you encounter the need or start with mockup to make the frontend structure flow?

In full stack / modern webapps and in general, how do you keep yourself directed and stick to the plan in order to achieve your target?