Hello Everyone,
It is my first post here in these practical groups, so i hope my knowledge and expirence will be helpful.
It is related mainly to media buyes who takes risk on running campaing getting paid for CPA and buy on CPM/CPC Models mainly.
I am not going to talk about reasons (why the CR/CTR is low/High, for example) but mor about facts, and how to use them.
So the main thing about building a media buying stradegy is first to know what do you exactly promote. For example, if we are talking about mobile content offers, it is important to know what is the actual content we promote, what is the flow (for each carrier, as it is a carrier billing) and what kind of media can we buy to this offer. Knowing that could help with kind of creatives and landers you might use.
Second important thing to do is media plan and this is the main topic here. I guess a lot of you having this dilema on which pricing model should we start with?
Well, first it is depend on your traffic sources. I like to start with 3-4 traffic sources, that each one of them has different type of media sell.
Here is a few steps that might help you:
1. Start with CPC if possible. The main reason for that is that you can easily track better from your tracking software after the stats and you can measure your sucess. For example, if my CPA is 10$ and i buy from a network on CPC of 0.1$, it means i need more than 1% CR in order to be breakeven. So whenever i see that my CR is higher than 1%, i am making profits. Of course, there a lot of ways to look at this P\L stats, but it just an example that shows the relation between clicks (what I pay for) and conversions (what i make revenue from) so this is why i like it. Second reason is that it lowers the risk of spending. Impressions are much more likely than clicks and nobody can ensure high CTR from the beginning.
2. Gather information about the top converting Segments (take a few days, unless you see some immediate insights). Best to start from the major ones such as: OS, Carrier, Country and go deeper to Publisher id (name), Devices OS, Manufaturers, Models and more. Try to collect these to start planning your next campaign which will be a whitelist of all segments that are beetr than others.
3. Look at the CTR. Why is that so important? Looking at the Eco-system of an ad-networks, most of the publishers tend to be more friendly with CPM buyers as it put the publisher in less risk (he gets paid for views, no need for him to pray for clicks to come and give him revenue), so the ideal here is to try and calculate the eCPM you generated from your CPC campaign (CPC*CTR*1000). NEVER FORGET: good CTR is nice but if it has no relation to Conversions than it is meaningless. So if you see a good CTR publisher with 0 conversions, think again if to gather him to the next plan.
4. Build your next Step. It could be a duplicate of your first campaign but only with the top Segments you gatherd and pick up the pricing model you preffer (I like to test both CPM and CPC). Try to make a Whitelist of these segment, and put a higher price of CPC if your wish to use this model again. When using CPM, look at the first campaign and see what is the eCPM generated. when you have in general high CTR, it means that you might consider use CPM becasue why paying for clicks when they are comming in high numbers? So for example if The eCPM you generated is 1$, and you know you can buy form this network at 0.5$ CPM, it might be a good call. You will lowerd your eCPC to half if the CTR remains like the first campaigns.
5. Whenever you make changes and try to go to the next step, TRACK IT CLOSELY. There can be always surprises, for good and bad.
Hope it will be helping you.
Good Luck! 
Good tips! Thanks so much NALUX for sharing your experience!
Amy