Cooking to the proper temperature is the most critical step. Insert a thermometer into a meaty part of the leg (avoiding the bone). When the temperature reaches 165°, pull the chicken from the oven. Let rest 10 minutes. You need to insert it parallel to the skin, not perpendicular.
So for the breast, insert near the wishbone and aim toward the butt, going in usually a couple of inches, not beyond the thickest part of the breast. For the dark meat, go into the thigh, parallel to the thigh bone from the "knee" toward the "hip". In no case should the thermometer touch the bone.