To make a proper Iced Americano, make the drink by adding espresso into cold water, then adding ice. By adding espresso after the water, you can get more crema from the espresso on the surface.
Freshly made espresso is best. Hot espresso is cooled down instantly by adding it into cold water.
Use an espresso machine or a Nespresso for best results.
There is no standard in the amount of cold water that's to be used in an Iced Americano, so use as much or as little as you like, depending on how strong you want the espresso flavor to be.
Iced Americano is usually made with dark roasted coffee. Use a blonde roast if you want a smoother flavor with slightly more caffeine or make it ristretto (short shot) for a less bitter taste.
The drink is made without any milk or sweeteners like sugar, but you can always add any you like.
Use filtered cold water for a better tasting Iced Americano.