When you are in the game, there are special commands available.
Emulators bring a very useful feature : save state. A saved state is a quick save of the game, and allows you to reload the game at this point.
With save states, you will never have to seek for a saved point again !
Hotkey + Y → Save State
Hotkey + X → Load State
Hotkey + Up → Select Save Slot -1
Hotkey + Down → Select Save Slot +1
Hotkey + Start → End Game and Quit To Main Menu
Hotkey + A → Reset Game
Hotkey + B → Retroarch Menu
Hotkey + L1 → Screenshot
Hotkey + Right → Speedup game
Hotkey + Left → Rewind (if enabled in options)
Hotkey + R2 → Next shader preset
Hotkey + L2 → Previous shader preset
In FBA and Mame, press Select to add a credit.
You can access the Retroarch configuration menu with Hotkey + B, If you want to configure retroarch and save the config, you can select the "Save Settings on Exit" in the retroarch menu. After that, all configuration you make in rgui will be saved.