One question regarding optimization. What rules do you guys follow for cutting keywords or placements, or reducing bids? (In mobile, native, Adwords or any source of traffic that you use)
The 2x payout rule? (If cost goes over 2x payout, cut or reduce)
I was trying to apply some techniques from mobile and native advertising in order to try to make profitable some new ppc keywords that we are working in. --- These are keywords with a higher CPC than we are used to, so we were looking for new approaches that could make them finally work.
It's a bit scary once you are spending "big money" per day just to "buy" enough data to know if a new keyword is gonna respond well or not, so I guess it's similar with native and other sources and we can learn things from each other that could work.
Thanks! 
For Adwords - I go with 1x payout. You've got to have your bids set correctly in the first place based on CR. Say you expect 10% CR and have 30 payout - your actual CPC shouldn't be more than 3. If you max bid doesn't get you to the desired ad position or brings very low CTR - the keywords might not be worth it or you should work on improving your CR.
I also cut keywords with xxx impressions 0 clicks.
There's a saying - don't fall in love with your keywords 
what about using CPA optimizer once you got solid data?
This is in relation to search/ keyword based ad networks like Google, Bing or Yandex.
From my opinion and experience with keywords they have their place, however they are just 1 part of the chain to what you ultimately want to get to.
Yes you want to cut keywords that are not relevant so you can redistribute investment to better performers, however there are multiple points to go over before just pausing and calling it a loss.
The things to consider;
1. Organise themed campaign structure (This will help you to see your reporting clearer)
1.1. Determine relevant campaign targeting (e.g. Country, Demographics(gender or age) & devices (Desktop, Mobile & tablet) for now)
2. Tightly themed ad group structure (This will help you to see your results and reporting clearer)
A massive plus to point 1&2 is with good structure you can apply bidding strategies to targeted campaign/groups saving you time and performance without affecting other groups that do not behave similar in performance.
E.g. ad group1 is performing well you want to spend the budget hard and fast to get more results
If you have a mixed themed group or campaign you cannot not be so direct with the approach of aggressive daily spending as each themed may not perform at a great rate. This also means things that do not perform well is eating your investment rather than being pushed to the top performers.
2.1. Determine relevant targeting of your ad group
3. Themed ad copy that compliments the tightly themed ad group structure
This is very important as this is the first thing your potential audience sees before they even want to see if you can solve their problem/s.
This has to be tested with varying different copy that is experimental.
Bad ad copy could stop you before you even get going even if you have good keywords, targeting or good end offering.
This is no different to seeing a beautifully well presented male or female you think is your type, if not presented or spoken properly potentials will most likely not be interested.
4. Relevant keywords to ad groups
Putting relevant keywords together allows you to then tailor your copy easier so it's not generic to your potential customer.
Plus bidding for different theme targets may cost you more, however creating a tightly themed grouping structure you can apply bidding rules, pause things easier than being mixed with different performers.
By taking the time to build a structure it makes it easier for you to do negative keyword adding across groups and campaigns, which can assist you to obtain better cpc rates and non relevant keywords activating at higher cpc rates.
5. Relevant keyword match types to ad groups
This point can be approached in several ways
a. Multiple match types can be in an ad group (broad modified, phrase and exact)
Majority of the keywords exact, a handful of modified to help you mine for potential keywords you would never of thought of and some phrase.
From my experience phrase match tended to burn the most investment over time so keep an eye on them longer term where as the quick investment burners was broad modified. It maybe different for you, however keep a close eye on it.
Depending on the terms getting you performance you can then place them into the ad copy to see if it improves your performance.
b. You can build your campaign and ad group structure together with themes and match types
This can be effective as you can utilitse this method:A to then build out to method;B or go straight out the gate with method:B.
This option can keep match type spending more in line and allow you to be more aggressive by match type and themes, however takes time and data to build out.
6. Device & demographic targeting
You will have to check you reports tool to see how each device performs due to your structured themes, which from what I recall can be controlled with percentage based bidding per ad group.
Mobile may work for you so you can increase your percentage bids per group, however desktop and tablet may not be worth it for you so you may want to decrease bidding to 95% or 10% so the spend or performance fits your goals.
Inclusive with device you can target by gender and age group. If you know your offer demographics then target them through the ad network platform. You don't want 18-22 year old for your war veteran product about PTSD.
To be honest those ad networks are have options which are a world inside a world as there's numerous options you can utilise, which you can get lost inside.
Focus on 1 network to get a solid foundation before moving onto another network as each network has their own rule sets on how to do things.
If you use any of the below ad networks make your life easier by using the software below to save you time and headache so you do not get side tracked by shiny object syndrome.
Google adwords: Google Adwords Editor
Bing Ad Center: Bing Editor
Yandex: Yandex Commander
Hope that assists you and enjoy (Απολαμβάνω as Greeks would say)
Thank you for the information 