I wrote about it here (https://www.indiehackers.com/blog/launching-to-300000-pagevi...), but basically I scoured "Ask HN" posts, built a list of 120 companies, tracked down most of their email addresses, and asked them to do an interview and share their revenue numbers for the site. I ended up launching with 12 companies a few weeks later. Since then most of my interview requests have been inbound.