Counterpoint to starting a business: the founder of Nvidia, who is worth tens of billions, says if he had it to do over again, he wouldn't. Starting and running a business takes a tremendous toll. https://www.forbes.com/sites/julianteicke/2023/10/28/jensen-...
If you insist on proceeding... Validate demand first; once you find something you're sure people want, you know a great deal about these people and enjoy working with them. You're sure you can find lots of them, and you find the core problem you're working on fun and interesting.
My dad told me... "A successful business is when you can do something badly and people will still pay you for it." That's key in a startup because it takes a long time and a lot of money to do most things well, so you need customers who will settle for ok.
Good luck!