English Setter coats can be done in two basic fashions. When used as hunters, the coats should be styled for maximum benefit. The hair should be short enough to catch the least amount of debris while in the field, and long enough to protect the dog from injury by said debris as well as sunburn, scratches, etc. Coat care is no less important for English Setters as companion animals. Because they aren't as physically active as when hunting, their coat won't get the natural raking from branches and brambles. Dead hair will need to be brushed out. Brushing also allows inspection for critters and other skin and coat concerns.
The Show Style, which has many variations, is nonetheless at its best when the dog's coat resembles a classic sea-going vessel with all the sails out. The feathering will follow the bone structure and fan out as if a great tailwind is indeed powering the dog's presence. Most obvious will be the feathering on the undersides of the tail, torso, and brisket.
It should be noted that the Show Style comes in two variations: the American Cut and the English Cut. The English Cut is described above. The American Cut is distinguished by the back being heavily clipped. The result is a billowing below the lower torso and slightly wavy coat hair on top.
The Sporting Cut is far less fancy, to be sure, but it is nevertheless a cut that allows the English Setter look to shine through. Nearly all the feathering is clipped away save for some on the tail, which allows for easier sighting when the dog points game. The ears are also allowed some feathering as this hair protects the inner ear.
Show styles are best done by pro groomers. You can learn how to do this kind of English Setter haircut, but beware that clipping the hair harshly or even hand-stripping the coat can result in less-than-silky hair when it regrows. Field cuts are easier done by less-experienced dog owners.