Here's a quick and easy way to make chain mail (mesh/stockings too). Take note that I'm doing this in Photoshop.
1) In the first screen I have the sprite and single pixel checkered pattern. Both on different layers. I always have this checkered pattern laying around for things like this.
2) Drag the checkered pattern over the part you wanna turn into chain mail, make sure it covers the whole area wanted.
3) Go back to the character sprite and use the Magic Wand Tool to highlight the empty space around the character. Then click back on to the checkered layer.
4) Paint bucket the checkered layer a different color. Since it should still be highlighting the empty space around the character, this should make it easy to use the Magic Erase Tool to get rid of most of the uneeded pixels.
5) Now you'll have to go in and get rid of the pixels that fall on unwanted parts (like the gauntlets, chin, and belt in this sprite).
6) When making a WIP, it's best to now color the checkered pattern black and take the opacity down to about 70%. Then merge the layers. This will make an easy smart pal on it.
7) This screen is to show how it can look when you change the colors afterwords.
Here's the checkered sprite layer I used for this.
Aquaman sprite by TwinImage