Here is my two cents:
-Airplane mode
•kapag naka wifi and/or
•walang hinihintay na call or text (almost everyone use messenger to communicate)
•kapag mahina ang signal ng phone (malakas humigop ng battery kapag mahina ang signal/pabagobago)
-Low level of brightness.
-Silent Mode
-Avoid using video something wallpaper/Theme (Yung gumagalaw sa screen)