Rough ideas I've played with over the last 18 months of running my business
- Writing content for your (potential) audience
- Hanging out and talking about the topic on reddit/Discord/Slack/HN/Twitter
- Setting my hotspot name to my project's domain name whenever I'm around techies or on long train trips
- Find any and all directories that might list products like yours
- Meetups
- Online ads
- Side projects as marketing (little tools that your audience might use, for free)
- Linkedin, talk to people you've worked with before