[bemmu]

I would spend a good chunk of time trying out many different ad networks. My traffic is very different, as I mostly have apps on social networks, but I could sometimes find that an ad network performed 2x-10x compared to another one. For example in my case AdSense paid 10x better than Cubics / LifeStreet even though those were geared at social networks.

Not knowing this I wasted thousands of dollars before that I could have had by simply slapping in a different network's ad unit. For my current app I am planning on spending several evenings applying to every ad network I can find and split testing them against each other to make sure I won't lose such easy money this time.

You could also try direct ad sales by simply reaching out to people over email. I only have one data point on this, but I once noticed someone advertising with Reddit self-serve ads that was selling a product very suitable for my audience. I emailed him, he PayPaled me and soon his ads were live on my site as well.