I see users struggling to get just the right rectangular, or elliptical selection in Photoshop. Then painstakingly trying to add or delete the selection to get it just right. If this sounds familiar to you, try this great little feature. Choose Select > Transform Selection. Handles appear around your selection, you can then grab an handle (anchor point) to resize your selection, or hold down the Control (Windows) or Command (Mac OS) keys, and then click and drag an anchor point, to distort the selection.
Press the Confirm button in the Options bar when done.