As a developer, if I need to pick a concept which I find most important in deciding the placement of information, then it is the user focus areas on screen. You want your users to find more important information swiftly so you keep those elements in the areas of the screen which get more focus and keep less important elements in areas which are less intrusive during user scanning the page. Have a look at following imaginary compartmentalization of screen areas:
Green dots represent user focus. So, 1,2 and 5 are the areas which are going to get most focus of user. Then come 3, 6, and 9. And the least focus grabbing areas are 4, 7 and 8. The arrows show the shifting of user gaze while they are scanning your app’s page. This shifting of gaze is closely related to the focus areas. User’s focus shifts in this sequence (not very strictly but generally)
1 > 2 > 5 > 3 > 6 > 9 > 4 > 8 > 7.
This can be a great guide to plan control/element placement in your app.