just practice with him. learn how to dodge and hit ur shurikens. Dont waste dash into an enemy with 80% health if u cant kill him. Genjis dash is the only escape abilitie u have besides from deflect. be effective with ur wallclimb. use it to peak over walls and hit with ur shurikens to get the extra ult charge. Dont think to much over ur accuracy. just try to hit as much as u can. if u see a low healt enemy dash into him and meele him. if u get the kill. ur dash will reset and u can get away
when u use ur ultimate. try try dash as much as u can, it helps a lot with damage and makes it harder for the enemy to kilk you. Allways go for the squishys first.