First, it is just very hard to make money from ad/donation supported niche content sites. I am running few sites like this for half decade and my income is basical half of what it was last year every year, even with 20%/year increase of traffic. It basically went from being able to pay my mortgage to paying for nice dinner each month.

I like what is described as The Stairstep Approach: https://robwalling.com/2015/03/26/the-stairstep-approach-to-...