Preparing the perfect shot of espresso takes more than just great coffee. The most important aspect is timing. As the espresso brews you can see it change from a dark color which is rich and flavorful to a lighter color which is thin with a bitter taste. The key is to stop the shot while the coffee is still rich and flavorful.

You can control the timing of the shot by varying the grind. Generally speaking, the finer the grind the slower the brew. You should grind your espresso so that the coffee starts to dribble out slowly after a few seconds and then take approx 20 seconds to brew, however, you should judge the length of your shot based on the color of the streams rather than the time.

Grind only the amount of coffee you will use immediately. Once ground, coffee will stale quickly and after only an hour there can be a noticeable loss in flavor. Consistency of your grind is also important for espresso. Blade grinders may work for a French press or drip but they generally do not produce the consistent fine grind that you need for a good espresso. Burr grinders are best for an espresso. It is important to note that to maintain the same timing on your espresso brewing you may need to adjust the grind regularly to compensate for changes in weather.

You should use 6 - 8 g of coffee for a single (1 oz) shot and 12 - 15 g for a double (2 oz) shot. Be careful to use the right filter. Don't just put less coffee in a double shot filter for a single. Tamp the coffee down in the portafilter using a firm even pressure and a slight twist. The surface should be smooth and level to ensure that the water flows evenly through the coffee. Remember if the coffee brews too fast make the grind finer. If it is too slow make it more coarse. If in doubt, stop the shot sooner rather than later. When made correctly, the top ¼ to ½ of your espresso should be golden foam, known as crema, and the shot should be flavorful but not bitter.