I've been promoting Changeletter through all my channels, including my own personal email list of 1,000 people (I honestly thought more would subscribe - sad).
I also hosted an event in SF and have been promoting an upcoming giveaway to drive more traction to my IG page & subsequently newsletter, and I've also personally reached out to friends and power users to tell more people about it. My goal for 2019 is 1,000 subscribers and I'm still very far off, but I'm 25% there!