You know that teenage kid in the produce department of the supermarket, the one stacking bunches of bananas on the display, the one you might not think can form a simple sentence? Ask him. Even if he can't manage the simple sentence, he can point.

Look for ginger with smooth skin - if it's wrinkled or cracked, it means the ginger is old. It should also be very firm to the touch. Finally, make sure it has a fresh, spicy fragrance.