How do you sell your services as a Web App Developer?

Hello everyone! This is my first post at dev.to I'm a self-taught Web developer and I have something on my mind and I would like to hear your thoughts about it.

I have been working as a full-stack MERN developer for a few months now, and I'm about to try to sell my services to some local businesses.

I already did make some websites for a few businesses out there, but now I would like to try it with Web Apps. I'm mostly doing CRUD apps with auth, not that much fancy algorithmic stuff.

Now, I wonder, what kind of apps would you try to sell (e.g Dashboard for keeping records about customers and sales) and what type of business would you contact (law office, some kind of medical clinic, etc...)?

I really appreciate your suggestions. Thanks in advance!