When I picked up this site, had good traffic but wasn't running ads.
In order to start monetizing I hooked up Ezoic. AdSense is a joke, and I didn't have enough pageviews for Mediavine. I've been using Ezoic for another one of my sites (http://manscipated.com) and have had good results. So I gave it a shot.
It was a bit tricky to figure out how to carve ad units onto the site without degrading the user experience too much. The previous owner (who was VERY helpful) had a couple of tricky Wordpress templates that made inserting ads a bit difficult - even with Ezoic's awesome Chrome Extensions. I had to hire some help from one of my VAs to get the ad units to show up properly.
It paid off immediately. Ad revenue started rolling in, and this site is now on track to make its money back in just 8 months. Sometimes it really is as easy as flipping on a switch.
My next step will be to hook up with Printify and add an Ecommerce store to the site.
If you want to run ads on your site, I highly recommend using Ezoic instead of AdSense!