The chord progressions in songs often follow the circle of keys, usually to the right. (By the way, the circle of keys is often called the Circle of 5ths or the Circle of 4ths, but it’s the same thing — just depends on whether you move to the right or to the left on the circle). Notice that the flat keys are on the right hand side of the circle, while the sharp keys are on the left hand side of the circle. Watch this short piano video and you’ll understand: