I have one trick, and I won't share it because it's very niche and my margins are very thin (well, still slightly negative...) so any competition would kill it entirely. But it came about as a result of closely looking at my audience, looking for ways to precisely target them, and creating ads in a way that that demographic likes.

Before that, I had some success using Python to generate many thousands of niche google keywords (e.g. don't advertise on "Learn Spanish", but instead "How to learn Estonian quickly" and "What's the best way to learn Hungarian online") and advertising on them. It didn't have a positive ROI for me, but it might for other people with larger margins.

Tricks exist, you just have to look for them. Remember that most marketing people can't code, and exploit that.