Been making clothes for a while now and I've seen a lot of posts on here about folds and wrinkles on T-shirts and such, thought it might not be a bad idea to put up a thread for people to post some tips on how to create realistic fabric effects in SL.
Anyways, if you're fairly new to photoshop like myself you probably just have no idea where to start. I find it helps to take a look at pictures of real people and just LOOK, examine how the clothing fits on a persons body and where the fabric bunches up or wrinkles on them. You want your texture to have wrinkles in the same general areas and it helps a lot to use the UV's on Chip Midnight and Robin Sojourner's clothing templates to see how it will map in-world. Ok, so once you've pulled up your template I like to start off with the burn tool, set your range to highlights and exposure to about 20% and a brush size of around 9 px to start off. Make a curved line near the stomach area of the shirt in an inverted arc, sort of like an upside down rainbow, (i know pictures would help but uh.... im lazy x_x) the line should be pretty faint so make a second one in the middle of the first so the middle is darker and it fades on the edges, you can repeat for a darker fold as many times as needed. Select the blur tool with 100% strength and a brush of around 20 pixels, blur the line to shade the tones in the fold a bit. At this point i like to use the smudge tool on with 45% strength on the ends of the line to fade them out with a few small strokes. Setting the layer type to Multiply seems to help a little too. I'm still pretty new to this so thats all I have for now, feel free to post any tips on this type of texturing and thanks for reading i guess.
but you'll get the hang of it!