I prefer using the ADB .

I prefer using the ADB. However, It's a little less user friendly. This isn't the easiest way, but it will work without an SD card and will work without the device being internet connected(some devices(tablets) aren't). At the command line you would type: adb install "full-absolute-path-to-apk-here.apk" The "tools" directory of the SDK must be in your path for the adb command to work.