Do you put ads, DM your network, cold outreach through email or LinkedIn DMs for B2B, post content if you have an audience, or what else do you do?

I'm more interested in the DM experience, as starting an inbound channel when you only need 1-4 customers to get started testing your idea seems an overkill.

How do you approach people through DM? Do you first try to simply make more friends and then DM those people? Do you get into the careers listings and try helping them with a demo of your product?

What else do you do?