- Install Heroic Game Launcher for Epic Games Store and GOG.com.
- Install ProtonUp-Qt. It is a tool to install different version of Proton (GE).
- Install EmuDeck. It is a Emulation Suit for the Steam Deck. It includes various emulators.
- Maybe avoid installing plugins at the beginning. Make sure your Steam Deck is working properly first.
- Play Games (?).
Almost forgot, before everything, you should drain your battery all the way to 0% to recalibrate it.
To do that, drain the battery to 1%, and turn it off. Turn your Steam Deck on holding the Vol- button, you should boot into the BIOS. Leave it until it turns it self off.
Now charge it until completely full.