"The image at the right shows my main image window. This image is a little smaller than life size, but in reality when I do this I zoom up the window until it fills my screen from top to bottom.
"Here I have turned off the layer that has the original Rogue skin by clicking on the eyeball icon next to that layer. So as I paint the mask with black, the underlying nude skin shows through. I'm almost done at the point I made this image, with just a little bit of yellow from Rogue's costume to mask away.
"I am painting solid black with the paintbrush tool, and have set the paintbrush's opacity to 100%. For this operation I am using a small circular brush with hard edges so I can get precisely up to the edges of the vest.
"If I wanted to have some of the background show through I could set the paintbrush's opacity to a lower value, but that's a trick to keep in mind for a different kind of operation. Our goal for this step is to completely isolate the vest.
"By using a layer mask to do this, if I don't like the results I can always come back and paint out part of the mask with white. If I had used the lasso tool to select the area of the vest, I wouldn't have that option, and instead would have to start all over or go through a lot of steps to meticulously adjust the area I have selected.
"The drawback to using layer masks to isolate bits of clothing is that the Photoshop files can get pretty big; but I have lots of disk space and lots of RAM, so I'm not worried.