1. Partnership with a domain expert in a then under-served niche market (he was a contract work client turned business partner). The relationship has been difficult, and for the last many years I have been the defacto sole participant. Having a pipeline to the market was invaluable in the beginning, though, and I was able to extract enough pain points from his experiences to put together an MVP.
2. In the beginning, we were crazy responsive to support requests and feature requests. I made the early customers ("visionaries") feel extremely supported and part of the process, and many of them are still with us to this day. Incredible support makes up for a lackluster UX, feature set, etc., especially in non-tech-savvy markets.
3. Despite #2, I said "no" a LOT. It's especially difficult to say no to domain experts who feel like they are the customer, and even harder to say no to actual customers. I prioritized maintaining simplicity of the app over all else; the competitors in the space had all overdeveloped, and especially for our non-tech-savvy market their apps became overwhelming. To this day, we still get customers from a company that hired Indian developers to clone our app. Every one of them says "it was just too complicated." http://www.programmerfu.com/2017/03/16/saying-no-for-fun-and...
4. Slow and steady. Bootstrapping affords the ability to take your time, and you're not hiring a bunch of people who know they'll get fired as soon as your funding runs out. Worst case scenario, you go into "cockroach mode" until you can ramp things back up. We have never hit the hockey-stick curve but we have very low cancellations and constant slow growth. Growing slowly also means the app and company get to grow with the customers rather than uncontrolled bursts of user growth followed by "oh shit, oh shit" and letting those new users down with scaling problems (both technical and human). Slow growth also risks a new, funded competitor will come in and blow you out of the water. Luckily, we didn't experience that while we were young and vulnerable.
This is a bit rambly, and I've got to run to lunch but I hope it's in the ballpark of what you're looking for. I'm open to answer questions as well :)
