Ask HN: How to Get Traction for Startup?

I am founder of a bootstrapped startup and don’t necessarily have big network advantages that others have. I am making use of my network. To validate an idea, I created and emailed a lot of people. However, most people don’t respond back. Reddit and other forums ban surveys flat out.

So the question is, besides paid marketing and spending big, how to get traction and initial interest in my product?

What are channels and resources that can help validate the idea before I build it spending 3-4 months?

Cheers.