How do you serve single shot of espresso?

A single espresso should be served promptly (less than 120 seconds after it's made) in a pre-warmed porcelain cup, with an appropriately-sized spoon on the side.

The coffee will be hot when it enters the cup (about 80*C), but one should allow it to cool a bit (about 65*C) before drinking.

Many traditional coffee bars will bring the customer a small glass of water on the side - to be drunk before the coffee, to ensure a clean palate. Drinking the water after the coffee will wash the aroma out of the mouth too quickly - and will suggest to the barista that you did not enjoy the coffee.