First, I DON'T go to Starbucks... they don' t have good coffee. Find a good shop with fresh coffee and a real Batista. Ask for an espresso, and drink it. If the shop is any good, they will have a well balanced coffee blend that is designed to be drank ONLY as espresso.
When you drink the espresso (no, don't add sugar, or anything else), take the time to inhale the steam, and notice the aromas in the steam... you should be able to smell Carmel, or vanilla. Then, sip the drink, and see if you can pick out other flavor notes. Don't ignore the finish either, it should be smooth, and pleasant.
Coffee, especially Espresso, when done right, is more complex than wine tasting, and should be treated as such.
Once you allow yourself to enjoy an Espresso, you will never go back to the other drinks.