Open a photo of someone who needs a nose reduction. I am using the photo below that I got from http://www.reflexstock.com:
Go to Filter > Liquify to open the liquify dialog box:
In the Liquify dialog, select the Pucker tool in the Toolbox on the left hand side of the dialog box (4th one from the top):
Put your cursor over the nose to see how big the brush is compared to the nose. Adjust the Brush Size setting on the right of the dialog:
and increase the size until the bottom of the brush touches the bottom of the nose and the top of the brush is right between the eyes at the top of the nose.
Move your cursor so the center of the brush is centered over the nose as shown above. Click once to minimize the center of the nose. Move your cursor so the center of the brush is over the outer left side of the nose. Click again to reduce that side of the nose. Repeat this for the right side, the bottom, and the top of the nose. You can repeat these steps again if you didn't get the nose small enough. Here is my finished project: