The biggest tip I can give is to pay attention to your positioning. Play around your enemies ideal range, know when to disengage from a fight, don’t panic fade(just position yourself close to escape options) etc and you’ll do great. Three other good tips I’ve picked up are, damage orbs 9/10 times give more value than healing orbs, you don’t need to hold down your healing spray unless absolutely necessary (you are a dot healer) and being able to position yourself to hit multiple teammates with your spray is critical, and last but not least you gain ult change extremely fast so you can use your ult pretty much when you get it rather than trying to save it since it’s great in many situations.
Another thing to take note is that maps with a lot of height are terrible for her. Gibraltar being the worst, so just be mindful of that.