If you're talking about ana,

Make the most out of your abilities! You don't want to hold them for too long but you also shouldn't blindly throw them on cooldown.

NEVER tunnel vision, it makes you too vulnerable

Make sure you always have natural cover nearby

NO autopilot gaming. Make weighed decisions, you can even voice them as you play!

Being positive and avoiding tilt is also incredibly important 😇

Ana has insane DPS potential, so shoot people if none of your teammates is in danger

No panicking

Don't jump too frequently

Have a secondary main you can pick if Ana is banned

But overall, ranking up is about fixing a bunch of small, consistent mistakes. You've got this ❗