In what order should you start optimizing your campaign?

[IgorSia]

Hello everyone
I read the guide on PopAds from @servandosilva, and he advised to start optimization in this order:

websiteID > devices > browser versions > OS versions > categories > Adblock etc.

I was wondering how who starts to optimize an ad campaign?
I usually started to optimize from the OS version, now I think that I always did it wrong
Thanks for the answers