Ask HN: How do you acquire customers without network or social media?

I am curious to learn about sales and user acquisition for first time founders in B2B software business. I don't have network or social media following for acquiring users.

What are ways that worked for nascent startup for acquiring B2B customers? I read the book called Traction and focusing on channel that convert. However, I feel at this point, LinkedIn members are spammed incessantly with messages. We rarely receive email reply. A few people have vouched for our idea and will consider paying.

I would love to learn B2B customer acquisition for new startups and how to go about acquiring customers. Please share your wisdom.