The usual way to adjust a curve is to select an Anchor Point with the Direct Selection tool and then click-drag a Handle in or out, up or down, or from side to side. Sometimes, when editing a curve in this way, it can be hard to get the exact results you want. When this happens, try click-dragging on the Curved Segment itself to push or pull the curve into shape. As you adjust the curve, the handles on both sides of the curved segment more simultaneously, giving you a great alternate editing technique.
Tip provided by Jeff Witchel, Certified Adobe® Training Provider.