Hmm, that's all semi-general; specific questions are the best
If I understand correctly, you want to know how to choose a shadow color in relation to the full-light color? If so ..
First you need to know that less light equals less value, more light equals more value. Value is king in describing form and distinguishing shapes. Edges are queen but that's a different story. Next you need to know what light is present in the shadow. You would be unable to see it if there was no light present. If there is truly just one light source and the environment was white - I believe the only difference you would see would be with value. However this is rarely if ever the case. Outdoors for example there is little running from the largest secondary light source there is, the sky. Any interference, be it secondary lighting or reflected lighting of a different hue will cause a decrease in saturation; indeed think of saturation as a measure of purity. Once you have calculated the value and saturation levels the proper hue is simple mixing - pull out a color wheel and tell me what happens when you mix yellow with blue.
I've set up several exercises in the Peer Project just to teach this sort of thing, namely exercises 3 and 4 - but check out the rest as well; won't hurt.
Creating Seamless Textures for Use with Brushes
1. Grab the source pic from http://www.imageafter.com/image.php?...fabrics095.jpg . Imageafter.com is a great site, be sure and check out their texture section. Open photo in Photoshop and with the crop tool select as much similar texture as possible, not here I've blocked out all the borders as they would be very recognizable in a repeating pattern. I've also ticked perspective in the tool bar for a quick rotation and maximization of texture area. Any distortion will be neglibile if done right.
2. Let's not kid ourselves, we're artists - crap at math. Under canvas size I crop again, this time by pixel in order to get some nice even numbers which I will be dividing by half in a moment. No one is going to mix an area of 3x2px are they?
4. Remember when we cropped the canvas from before? Come on, that was 2 steps ago! Divide total length and total width by 2 and input them here. Make sure wrap around is selected!
5. The healing brush is perfect for filling in seams. Reminds me a lot of welding actually. Anyways - I still haven't got the hang of it and needed to use the clone stamp to go over a few ugly bits.
6. All done. Can barely see the seams, it's not the best job - but we're not using the photo, we're using it's texture. Things like the lighter band will show up in repition, however this file is rather large and the way the texture is used it shouldn't be too noticible.
7. After you have selected everything (Ctrl+A) Proceed under the Edit Menu and select Define Pattern.
8. A dialog will pop up, name it whatever you want. I think this is like italian for canvas or something ...
9. I'm going to use this texture on my favorite round brush. Minimum diameter is set to 70%, not too small - not too big.
10. I prefer to have opacity and flow to pen pressure on just about everything. I practically never touch manual opacity but manual flow is very handy.
11. Ok, back on topic! Tick the texture box and select our new texture. (Lil' downward pointing triangle next to invert.) Set Mode to Subtract (But please play around with the other modes and see how you like it!) Invert is selected because I think it looks better - more like paint that get's stuck between the texture rather than the texture of the canvas itself.
Infinit: My pleasure homey. Man, you really should be a hot female.
Cwn Annwn: Aww, I you too. Hope this garbage makes some sense
Utum: I have a few more you know Thanks much!
Asatira: My pleasure, have fun!
DIMAGYAN: Thanks much, glad you are enjoying this compost heap.
MeTaL-Mike: Yeah dunno what that is all about: new link - http://www.divshare.com/download/2221633-d96
Going to put up some video demo's tommorow or so... Just have to get a few files I left at work
thanks for the brushes man. I have to say i really love the stuff you paint man. i have great problems painting digitally, especially with color. it's very hard. looking forward to some new demos here, and in the mean time.... D: