Velvet Texture - Roarey Raccoon

First, we start with a simple line drawing, and what do you know, it's a peice of cloth!

The first thing to do is to pick a hue that you think is sexy, I chose teh blueness.

Now that we have that shizz, the next thing you do is use the crease lines to do a very basic form of cell shading, obviously I've done it crap for this quick example but meh. So you shade it all basic and stuff.

Now, I only use 3 colours here, for the colouring, because you REALLY don't need any more. Use the original colour, another one that is a few tones darker and the final one that is a few tones lighter (make sure that it's not too bright, v. important).
The next step is to go nuts; I started with the lighter tone, but you can start with the darker one if you like, makes no difference whatsoever. Basically, what you do is you extend the parts you have shaded by randomly dotting the pencil tool all over the place. Note the fact that it is DOTTED around, and not lines, because that's a different texture altogether. Break it all up and go nuts.

Okay, once you've done that, you do the same thing again with the darker tone.

Aaand finally, because some of the large areas of shading look too bland, like that really big light section near the right side of the cloth, get your original tone and do the random shizzle over the shaded area a bit too. Once you've finished, you should end up with this ghey.
Obviously, this gives the texture a kind of velvety effect, which you may not want; if you really want a finer texture then keep the tones closer together (ie not too different in colour) and do a more subtle job of the randomness.