Most people report a very good success ratio by cutting down caffeine intake at the rate of 1/2 cup of coffee a day. This is known as Caffeine Fading. Alternatively you might try reducing coffee intake in discrete steps of two-five cups of coffee less per week (depending on how high is your initial intake). If you are drinking more than 10 cups of coffee a day, you should seriously consider cutting down.
The best way to proceed is to consume caffeine regularly for a week, while keeping a precise log of the times and amounts of caffeine intake (remember that chocolate, tea, soda beverages and many headache pills contain caffeine as well as coffee). At the end of the week proceed to reduce your coffee intake at the rate recommended above. Remember to have substitutes available for drinking: if you are not going to have a hot cup of coffee at your 10 minute break, you might consider having hot chocolate or herbal tea, but NOT decaff, since decaff has also been shown to be addictive. This should take you through the works without much problem.
Some other people quit cold turkey. Withdrawal symptoms are quite nasty this way (see section below) but they can usually be countered with lots of sleep and exercise. Many people report being able to stop drinking caffeine almost cold-turkey while on holidays on the beach. If quitting cold turkey is proving too hard even in the beach, drinking a coke might help.