"Hi [name]! I publish a newsletter with x+ subscribers that highlights the workspaces of creative individuals and would love to include you. Let me know if you're at all interested! :)"
I think the earliest guests simply liked the idea of the project and thought it would be fun to share the workspace that they spend hours of their day in.
Now I think people agree because they are able to plug their projects in front of thousands of readers.
What was the first "x" you used in that message early on? How did you get that many of initial subscribers?
It seems to me that the only way to bootstrap something like this is with ad spend or viral social media content that inspires people to subscribe, but that's sort of a chicken and egg problem if you don't already have wide reach.
I think these early guests simply loved the idea of being able to share their space with their community so probably gathered all of the content for themselves and then had no issue sharing with me as well.
I have never spent on ads or any sort of growth driver like that. All organic to this point.
It's not as chicken and egg as it may seem. Let's say you want to create a newsletter about, oh.. TCP/IP, say. You write some interesting articles about TCP/IP related topics, interview some people in the field, put together some cheat sheets or something.. build up a useful Web site about TCP/IP teasing your newsletter somewhere on each page, submit things from it to Hacker News, Reddit, and relevant places enough, and eventually something will work out.