This is where version 1.2.1 shines. Newer "beta" builds of emulation software are often prone to random crashes or save-state corruption. In my testing of 1.2.1 over a week of play, I experienced zero crashes to the desktop. The save-state functionality is reliable, and the "Exit Game" function actually works cleanly, returning you to the main menu without hanging the audio driver—a common annoyance in other forks.

On your Android device, go to Settings > Security > Install from unknown sources and allow your file manager or browser to install apps.