Lots of great advice in this Twitter thread by Aaron Mahnke about how to start and maintain a popular podcast. I was particularly encouraged by this piece:
STICK WITH IT. Don’t give up after six episodes. Growing a podcast from zero to success isn’t an overnight thing. It takes patience and courage. You need to hold on and work hard. There are a TON of other podcasts out there, and it’s going to take a lot of time and hard work to float toward to top. Refine, improve, and get better. You don’t have to be 100% perfect in the very first episode.
Aaron Mahnke’s Lore podcast is one of the few that’s even spawned an Amazon Prime Original series. (Note: Amazon is my employer)
See also: Brian Koppelman’s advice about not giving up.