1) Do a thorough search to find out if it already exists.If you find it does, do not give up on your inspiration too hastily.
2)Talk to others about your idea, especially people you trust.
3)If your idea has support, then consider developing an MVP, or minimum viable product, to determine if it is a product you and others would really use.
4)If your testing goes well and you feel that you might have a winning idea, start building a brand around it now.
5)Ask questions like
i)"How do I get my first customer?"
ii)"How do I get my n-th customer?"