What to do before bring phone to technical assistance?

[Marco Arrichiello]

Hello, I've a problem with the screen of my Samsung A5 2016. It flashes like a "burning" light bulb.
Considering it still have a warranty, I want to bring it in technical assistance to repair.
What I have to do to completely backup and reset (even pictures) it, and then to restore it easily? I know Samsung Cloud, but what about pictures

 

[Itsa_Me_Mario]

Google Photos.