when and where to show ads in android application
I already integrated admob and madvertise to my apps but revenues are pretty low although the downloads and installs are ok/high. one of my apps is a little converter tool, the other is a small casual game. 

now i wonder what is the best way to show and place ads in my app. 

 1. I try to show an ad in the onStart method and destroy it in the onStop method as the Activity Lifecycle says in onStart the activity becomes visible to the user. is this ok or will it increase the total number of requests/impressions and so decrease my CTR?

 2. Should I show ads in activities which are only viewed for a short time e.g. main menu-activity, the level choose-activity or the profile-activity? Or is it better to just show ads in the game-activity as this is viewed for a longer time? 

 3. are there other certain rules/guidelines for when/when not show an ad in an activity?

thanks in advance
when and where to show ads in android application
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I already integrated admob and madvertise to my apps but revenues are pretty low although the downloads and installs are ok/high. one of my apps is a little converter tool, the other is a small casual game. 

now i wonder what is the best way to show and place ads in my app. 

 1. I try to show an ad in the onStart method and destroy it in the onStop method as the Activity Lifecycle says in onStart the activity becomes visible to the user. is this ok or will it increase the total number of requests/impressions and so decrease my CTR?

 2. Should I show ads in activities which are only viewed for a short time e.g. main menu-activity, the level choose-activity or the profile-activity? Or is it better to just show ads in the game-activity as this is viewed for a longer time? 

 3. are there other certain rules/guidelines for when/when not show an ad in an activity?

thanks in advance