We talked about testing ads. Then we talked about testing audiences. But do not forget to test media and/or platforms. If everyone's advertising on Facebook, maybe you'll gain traction on banner ads. The very media that you wrote off because experts told you banners were dead.
Testing ads is necessary, but do you know you can also test audiences? Your content and offers may have traction with people you never imagined would become your customers. Tertiary markets are blue oceans. Primary audiences are red oceans.