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?

I don't practice in aim labs or something I just do a warmup routine in range but I just wanted to clarify that will it have the same affect if I do it before playing competitive rather than doing it as soon as I wake up?