I like the idea of placing authentic creatives that you made yourself across adnetworks. Testing the different sizes and other people traffic while you develop your own.
Buy and sell ads at JuicyAds
Also might want to try
PlugRush for any feeder traffic.
Then it's a matter of testing and finding the right target.
(Yes. It takes a little money to make money. Don't be cheap because you won't see accurate results and only hurt yourself.)
Get social media accounts as well to push your brand.