It was a plugin, so I relied on the plugin directory to do the marketing for me. Other than that, it was priced competitively. Enough people matriculated through. The app itself sucked (was new to programming), but it did made money.

Since then, I've actually tried to do a lot of what's considered "best practices". Ironically, none of these techniques (which many thought leaders promote) actually worked for me. It may have worked for them (eg. prelaunch list building, getting influencers to use their app and promote it) but as a relative nobody, I think the rules are different for folks like me. I like to think I need to be scrappier and to simply do things that are counter-trend.

I suspect there's a large contingent of developers making a decent side living who aren't really talking much about things (too busy, family, other hobbies) and what they did to get there. Sometimes it's luck, sometimes it's just doing really dumb (but obvious in hindsight) type of things.

Over the years, I've grown skeptical about a lot of existing indie start up dogma that's been built up over the years.