Hi Stephen,
I've done some investigating in making skins, and one thing I can say is to be prepared for a lot of work!
A few pointers I can give you:
Detail is good AND bad. Using digital photographic information can enhance certain parts of the skin, and can detract in others. Too much detail can make a skin look "blotchy," especially if your photos show a lot of veins. Lighting will also be a factor. You will have to find a balance that works for your tastes.
When using the templates, realize that they are not exact, they are guides. Allow plenty of bleed over the edges to allow for seam coverage. You can always sample the colors near the seam edges to match them up. Anything you can do to help hide the seams will improve the skin.
Unfortunately, nobody is going to provide a skin texture set for you to copy from (if you do, it's probably not a skin that would help you). However, the clothing templates available in the downloads area of the SL website are the templates you need. The skin actually consists of 3 textures: (1) the head, (2) torso/arms and (3) from the waist down. You can actually use the templates to make a gridded skin, to see how everything fits.
I believe the templates are still named:
"CMFF-Master_Template-Head"
"CMFF-Master_Template-Upper"
"CMFF-Master_Template-Lower"
Get the PSD versions, they are more precise and layered - giving you better control over the needed information (seam and edge matching guides). Chip Midnight created them, and they are the standard.
(the page seems to be inaccessible today, but but this is one location to get them)
http://secondlife.com/community/templates.php You can make a skin from any graphics editor, Photoshop will do everything you need, as will most other editors (personally, I use several, but mostly gimp and Paint Shop Pro). I would recommend an editor that supports layers (PS, PSP and gimp support layers).
Also, expect to upload the textures several times, even with a clothes previewer. Examine your development in different lights and views in SL. Good designers have persistence.
The eye lashes have their own little area on the template - in the upper right corner of the texture. The eye lids should be black, I believe. I'm not sure how it uses this information, but I believe that SL has this area reserved
I hope that gets you a jump-start. Good luck!
~ V ~