Making a great cup of espresso coffee at home (assuming you have an espresso machine with which to make it) starts with buying espresso coffee, whether in whole bean coffee or ground coffee form.
For the most authentic cup of espresso coffee, look for the right coffee roast. Traditionally, espresso is made from coffee beans roasted so dark that they're almost black in color. These may be labeled "espresso coffee beans" or "French roast" or "Italian roast," any of which will yield the familiar thick, rich, dark brew. Do not, however, think that you must limit espresso making to espresso roast coffees alone. When ground finely enough, any type of coffee or coffee roast may be used in an espresso machine. If you like, have fun experimenting to see what results when you brew one of your own favorite coffees espresso-style.
Look for espresso coffee beans anywhere that features quality coffee and has a good turnover of freshly roasted product, to ensure that the espresso beans you buy will be as fresh as possible and have maximum flavor. Outstanding espresso coffee beans can be found in specialty coffee shops and through the Internet.
If at all possible, the best option is to buy espresso coffee in whole bean form, to be ground fresh each time it is brewed. Store the coffee beans in an airtight container at cool room temperature or in the refrigerator, and don't buy more coffee beans than you'll use within a few weeks.
If you don't want to bother with grinding whole bean coffee yourself for espresso, whether over concern that you might not grind it properly or simply because you don't want to deal with the fuss or the mess, don't let that stop you from buying espresso coffee. Feel free to buy the coffee already ground, making sure that you request "espresso grind." When you do so, don't buy more ground coffee than you are likely to use within one week, and store it airtight as you would for whole bean coffee, to safeguard the espresso coffee flavor as long as possible.
Another option is to buy espresso coffee in prepackaged, airtight-sealed coffee pods for use in one of the popular new pod system coffee machines. Prepared from premium espresso roast coffee beans and perfectly ground for the ideal extraction, espresso coffee pods present a foolproof way to brew the perfect cup of espresso coffee.