Case:
You want to run/debug Android app on your phone (e.g. Samsung Galaxy S2) instead of emulator (which sucks), but Android Studio (Windows version of it) can not see it among available devices.
Solution:
FIRST OF ALL The last thing you will think it is important, but it is indeed: install on Windows USB drivers for you phone model!!!
For instance:
Samsung Galaxy S2: http://www.samsung.com/us/support/owners/product/SGH-I777ZKAATT
LG L9: http://www.lg.com/us/support-mobile/lg-LGP769BK
Then enable some phone settings:
Developer options / USB debugging
Security / Unknown sources (Allow installation of apps from sources other than Play Store)
