Ask HN: How do you effectively promote your newsletter or podcast?

I've recently embarked on a podcasting journey in the niche of data products. I'm excited about creating valuable content, but I'm curious to know: how did you go about acquiring your first 100 subscribers?

Did you leverage social media platforms, collaborate with influencers, utilize email marketing, or employ any other innovative techniques? Any insights or tips would be greatly appreciated as I kickstart my promotional efforts. Thank you!