Utilize your jump more in ult to avoid damage as well as focus on having 1-2 easy 200 or less targets you can easily double kill before unsheathing the power of the dragon. Utilize your shurikens to soften up targets from a safe distance before hard engage and look for key cool downs that can negate your blade that may be up. Always try to keep a timer on zen and Lucio Ults or if they are even on enemy team.
You don't always have to dash upwards, dashing upwards before blade is primarily for Ana to nano you if there is one. Sometimes it's better to dash through your enemies to do damage then pull your blade out and then slash and cancel with dash for fast kills. Also understand you don't always have to jump when moving with genji because it will mess with your aim and don't always double jump because then you'll be more predictable. In terms of deflect always wait a split second for the enemy to focus you such as a widow because they do like to look at you to bait your deflect but if they don't see you deflect then they'll shoot you. Making reads on your enemies with deflect is a very important skill that can win games such as deflecting a zarya grav.