By specializing. I develop mostly for mobile and also work on smart contract architecture/servers for early stage startups. I don't do any "content-marketing" on LinkedIn, but just reach out to early stage startups seeing if I can help them. In my experience leads are best generated when you have a previous experience that shows to the client that you can develop the architecture/application. Then, if you sit down in an hour or two and hash out what a basic MVP would look like for them, they're confident you can deliver the product because you can explain how it would work on a technical level. Of course, that architecture will most likely change/improve as the product moves along but as long as you can show an iterative and constantly improving approach that's what matters.