I was testing my APK file on devices but it failed, while on emulators it runs successfully, so I need to enable debugging with logCat bundled with Android ADT (eclipse or new Android studio IDE).
So you need to connect your device to your computer via OEM USB driver, to deploy debugging APK package to your device to test from your IDE or command line.
But wait you will not be able to connect to your application and get it's runtime log, unless you enabled Developer options on your phone.
To enable it on most devices running Android 3.2 or older, you can find the option under Settings > Applications > Development.
On Android 4.0 and newer, it's in Settings > Developer options.
But note carefully: On Android 4.2 and newer, Developer options is hidden by default. To show it here is the magic, go to Settings > About phone and tap Build number seven times.
Return to the previous screen to find Developer options.
Happy debugging :)