This post is result of my test in Megapu.Sh. I’m a greedy person, so I really like to buy cheap traffic and try to monetize it, also it gives me an opportunity to make more tests.

Desktop push ads – better for tests (just my theory)
Most of all push ads case studies about mobile traffic. That’s because of CR on mobile traffic always higher than on desktop (of course there are some exceptions but whatever). The second reason is that amount of mobile subscriptions higher in 5-200 times. But to make some tests (choose an offer for ex.) desktop would be more comfortable.
So I have made first of all desktop campaigns. If I have positive ROI I create a copy on mobile.
Countries to start
Main idea – buy cheap traffic (CPC 0,1-0,2$) . After that I was looking for countries with rather big desktop audience in MP – 20 mln+ (exception if some of offers goes really well – then OK I could try to make creatives on each and every geo of this offer).
And in your affiliate netowrks should be offers for this geo (for example it’s really difficult to find offers for Afghanistan).
Creatives, countries and offers, that have worked for me
Money amulet
Azerbaijan Greece Kazakhstan
Man’s nutra (ACE)
PC game (World Of Tanks)
I’m making creatives by myself for CIS regions or English speaking countries. When it comes to other regions I cut text from landing page, paste it in google translate, find parts that would be good for heading and main message.
Some extra stats

Dear ….
I want to take training from you ……can you help me ??
Waiting for your reply .
OMAR FARUK
Hi, could you describe your problems/questions?
GIVE ME YOUR EMAIL PLEASE
Why do you need it?