I play on 400dpi 0.14 to counter my really shakey aim, problem is sometimes I get tired with all the movement I use in my arm to turn, any tips on improving aim and crosshairplacement on higher dpi/sens?

So i was just playing comp with randoms i died in some round and our chamber uses his ult and his ult sniper has a skin? (its not photoshoped i promise even my teammates saw it) https://preview.redd.it/a44vdkxdngv81.png?width=1255&format=p...