Here is my product: https://matchkraft.com/. It is a marketing toolkit. I think you need to ask for feedback, asking why users don't want to pay for a premium subscription. So far, you are getting new users that is a good sign you are going to the right direction. Maybe, who is your ideal customer or maybe your product is ok but need more visibility (maybe paying ads). Try to get active users. I really want to... Source: about 1 year ago

Calling a 3rd party API: There is a complete ecosystem providing "google-sheets-as-DB". I personally tested and recommend https://sheetson.com/ but there are a lot more with free tiers https://sheetsu.com/ https://sheety.co/. Source: about 2 years ago

You can start by subscribing to newsletters that can give you some exposure to all these topics and you can learn at your own pace. WSJ newsletters are pretty good. I run a stock market newsletter targeted for casual and beginner investors https://bullish.email. - Source: Hacker News / over 2 years ago

When the pandemic caused havoc in the stock market last year, my husband and I developed https://bullish.email/ - a daily newsletter that delivers important stock market info without frills. It is simple, clean, and valuable. We send stats (futures, performances, etc) before the market opens and after it closes (top gainers, losers, and performance). This way, you don't need to look for info; you consume it. Source: about 3 years ago