Ask HN: Side project promotion strategy

With inspiration from [1] i am wondering about your side project promotion strategy. Main goal: Obtain paying customers. Which marketing or promotion strategy works for you as best one? You can also share what and why (if you know) didn't works for you. I am especially interested in: 1: Niche (like gamers, designers, artists etc.) 2: Strategy compilation/description 3: Invested money and revenue (monthly or annually) [1] https://news.ycombinator.com/item?id=12065355