Forgive me if this has been asnwered....

Just a simple question....how might I go about defining the muscles (abs, chest, arms, etc) on my avy to look more realistic? Im no n00b to PS or anything, just to skinning in this game. So far I have taken the upperbody_shading_alpha.tga and have used a few screen blend modes to make it brighter but it seems to make it look even less realistic and defined. I tried the upperbody_highlights_alpha.tga using the same technique but it didn't look quite right.

Should I do some manual shading with a brush or is there another way? Is there another file I should be editing? Thanx for any help you guys give me and sorry if this has already been discussed.

I wouldn't get into the habit of changing those files. They're great to use as guides for creating your own shading maps for skins, but I would caution against editing them directly. Any change you make to them will affect every avatar you wear. You might come up with something that looks good for one specific av, but as soon as you put on a different one, it might look terrible. Also, the effect will only work while you're using the specific computer with the modified files. Use a different machine (or just re-install SL on the same one) and your changes won't show up.

A much better strategy is to make a skin (applied to the av inworld as a set of tattoos) that has the shading you want painted right onto it. It takes a lot of practice and artistic skill to pull it off, but the results can be quite good if you do it right.

Judging by the way you worded your question, I'm guessing you're probably already a competant artist, so it probably won't be too big a deal for you, technique wise, to do the painting itself. Learning how to make everything match up across seams though can be maddening, even for the most experienced artist. I'd recommend downloading Chip Midnight'ss and Robin Sojourner's advanced templates (both available on this forum). Both sets have high rez UV maps and seam matching guides on them, which are very helpful.

Just so you know, with the way the UV's are set up, torsos are pretty easy, lower body parts are pretty straight forward, but arms are very challenging, especially around the shoulder area. It takes a lot of practice to get it right.