There are a few ways to crop hair in Photoshop. The first way is to use the Selection tool. To select a part of your hair, click on it and then drag the selection around. You can also use the arrow keys to move the selection. The second way is to use the Curl tool. To curl a part of your hair, click on it and then drag the curl around. The third way is to use the Levels tool. To adjust the levels of your hair, click on it and then drag the slider left or right.
