Ask HN: Product development as a service business. Has anyone nailed it?

I have a small service business where we help founders without technical team build their products. We're a team of 13 based in India.

But the challenge I'm facing is, I don't know where my potential customers are, or how to reach them. Except that, I have leads coming in from my network but not always predictable.

Has anyone here really nailed this kind of business where the target customer group is so scattered and "hidden", that you cannot find them?

Is there any predictable sales method for this kind of business or is it not suitable for a business?