copy your darkest channel then use it as a fill by using selection -> load selection..then choose your channel.
This allows you to fill with different colors etc. and test many different looks easily without fucking up your original artwork.
I also keep a texture only file with tons of channels alreaddy created and then I just drag them into my working document and go through the above process...couldnt live without it.
i do the texture shit via computer too, but i have no idea what this table channel nonsense is all about i scan the texture. adjust the levels to get the most contrast then go do a select > color range > shadows.
You can also get a bear to mawl your final prints.
you can either do it by hand. like paint the shit, or you can do it in photoshop by scanning a texture and knocking it out of whatever you want to fuck up. Obviously the first of the two options is the most genuine but the second of the two allows for a lot more control.
how do you get that 'craped-up' effect where it looks like the paint has flaked off? is that custom brushes or do you do that by hand some how?
ive seen you use it frequently in your projects and it really adds alot.