Should I Build a Mobile App From Scratch or Start Small?

I have an app idea for my business, but I’m unsure how to turn it into something people will actually use. While researching app development services, I came across High10 and started wondering what matters most when choosing a developer. Should I focus on user-friendly design, app security, or testing with real users first? If you’ve launched an app, I’d love your honest advice. What would you do differently if you were starting again?