The Clone Stamp is the bread and butter tool for a lot of photographers, and rightfully so: it's a tremendously flexible and powerful feature that's strikingly simple in its operation, particularly compared to many other tools. This helpful video shows you a couple of quick shortcuts to get even more versatility out of the Clone Stamp.
I love the Clone Stamp; I use it for a huge proportion of my retouching. I personally think it's the quickest and easiest ways to do a lot of touch-up work, and with some careful attention to things like brush hardness and blending mode, it can convincingly handle a wide range of situations. This short tutorial from Unmesh Dinda of PiXimperfect shows you two quick shortcuts to increase its versatility: changing the angle of the area being painted on and changing its size. Using a different angle can be great for wavy patterns like fabric, while changing the size can be used for a multitude of purposes; just pay attention to the resolution of the cloned piece to make sure it doesn't become too blurry from being overly enlarged. The Clone Stamp actually has a high degree of customizability in its dedicated dialog, and it's worth checking out the options. You can see Dinda's full-length tutorial on it here.