The bowhunter's ultimate goal is to disrupt a turkey's circulatory, neurological, muscular or skeletal systems so it is immobilized or disabled to the point where it cannot escape.
To accomplish this, you must hit one of several primary aiming spots: the head-neck-spine, the vitals or the upper legs. Where to aim depends on the turkey's orientation and posture.
The head-neck-spine area contains the turkey's primary neurological systems. It is a small, vertical target zone, but a hit will typically immobilize the bird, often killing it instantly. This shot can be taken from almost any angle but is best with the turkey facing away, as this exposes the greatest target area (except on a strutting tom). It is also preferable that the turkey's head and neck be upright, and not tucked into the body.
The vital area is about the size of a man's fist and contains the majority of a turkey's blood and life-sustaining organs (heart, lung, liver, etc.). Unless the broadhead also strikes bone, a turkey hit here may travel some distance before succumbing. Turkeys use their powerful legs both to run and launch into flight. A shot that breaks one or both upper legs will significantly impede the bird's ability to escape.
The broadside shot presents all three aiming spots. Vital organs lie inside the upper half of the folded wing, beneath the wing coverts. A low shot will still break one or both legs.
A high shot will break the spine. On a strutting tom, aim forward and up to the leading edge of the coverts.
On a quartering-away shot, consider both the entry and exit location and move your point of aim back, much as you would for a deer. Unless aiming for the head, quartering-to and head-on shots are less desirable, because the vitals are protected by dense feathers, meat and breast bone.
While a poor option for other game, straight away is a good angle for turkeys. In an upright posture, the full length of the spine is exposed. A miss just to either side will still hit vitals and may hit a leg. On a strutting tom, the fanned tail provides a perfect bull's-eye and obscures the turkey's vision, allowing the hunter to draw undetected.