Loot quest items?

Hello!

Im kinda new to this thing, but i really want to try it out. But I have a very big question about this and I can't find any answers to it. My question is when you are out in the world and questing how do you loot quest items? Do you loot on each char or do you use a macro/addon for it? I found it out that you can't level up on only slay quests and I can't see a good point in being grinding up to level 70 so please help me!

// Your new friend Nivek

I tried a macro in another thread, but I can't get it to work at all

Looting via Keybind