Windows Phone Store certification and policy team has published a list of common failures that developers commit during the development phase in addition to the steps to avoid those costly errors, which result in delay in app release. The first and foremost requirement is related to app screenshots which should not include any emulator chrome, frame rate counters or debug information either in altered or in transparent state. Developers should make use of the built-in emulator screenshot tool to capture screenshots as Windows Phone 8 SDK ships with emulators for WVGA, XVGA and 720p resolutions.
Moreover, screenshots in WVGA resolution should be captured using the dev center feature that automatically scales the XVGA screenshots down to the WVGA resolution. In case if you intend to provide localized apps then you should include one screenshot for each supported language.
If you submit an app which requires login credentials you should include details of a dummy account in the certification notes in your dev center submission so that the relevant team will be able to test your app completely. If you fail to include this information then your app will be rejected and you will be required to again resubmit the app which will ultimately delay the app release.
As a developer, you should take steps to prevent the app from unexpected termination during the testing phase by making use of tools such as BugSense and Little Watson, which enables you to collect unhandled exception telemetry data.
Visual Studio, App Studio and Apache Cordova provide icons and tile images which you can use in your apps. However, Microsoft suggest you to replace them with your own images since the default images only pin point the required size.
According to Microsoft, back button should close the app only if the app is on the main page. It should go to the previous page only if it is not on the main page. Moreover, the back button should close an open dialog and soft keyboard.
Microsoft suggests developers to include a localized app description for each supported language using the built-in emulator. Moreover, you should also make sure to build the app in such a way that it displays properly in both light and dark themes. If you use Visual Studio you can easily toggle between the dark and light themes during the development stage.
Mike Francis of Windows Phone Store certification and policy team provides the required code for testing the current app theme including few tips for enhancing the quality of your Windows apps.