Use keyword search tool to find searches that have no high quality results. Then write a blog post for that topic and post the link casually on Reddit comments, twitter, etc. then wait a few weeks and it will be the #1 result. I have used this strategy for several years, it basically comes down to writing quality content on topics that don’t have any content.
Here's a guide from a few years ago that explains in detail how to follow the strategy. I don't bother with the really esoteric tweaks because the 95% solution is to identify keywords, write good content, and spread it around the internet.
I focus on the "long tail" because as a side-hustle entrepreneur you will never rank on the very popular keywords. You must monetize a lot of lesser-searched keywords, which in aggregate equal one very popular one, and you don't have to defend it obsessively.
You don't necessarily have to get a lot of traffic in order to generate revenue. There are potentially profitable niches that are not monetized at all.
That would be true if the number of topics in the world were constant, but new topics materialize all the time, and the popularity varies on old topics. Articles get old/outdated and are fertile ground for new articles with updated information, etc.
