On a ana zen it’s simple,
You need to take positions with the widest los available on the fight taking place so you get full view and can support everything taking place.
Remember range is not a problem on ana and zen
That said make sure it’s near cover and in a way its not on the main focus lane of your team , so you don’t take spam and if enemy want to focus you they have to split attention.
Obviously you need to change this position in accordance to if they have snipers then it’s best to cut los to sniper but maximize rest
If it’s dive either play close to other support of they peel or even further away so that they need to expend resource to get you.