Photoshop Tip - Crop with Perspective

I learned how to crop adjusting the perspective. Click on the Crop icon or type c to get into crop mode. Draw the box around what you want to crop. Click on the perspective check box. Move the individual corners of the crop box to the corners of the item you want to crop. Click on the check mark to complete the crop. Now if I could learn how to adjust the perspective without cropping. Always learning.