as a shannaro staff member, i have to tell ya, if you're just looking for shortcuts to get around having to do alot of hard work manually, then you wont find any, cuz none exist... there are helpful things that make things easier, yeah, but there will ALWAYS be things that need to be done manually...
to make lines and anything else darker or lighter, hold Ctrl and press L to bring up 'levels', a very handy tool if you know how to use it properly; play around with that and you should see how nice it is. this can only darken and/or lighten things, and often times you need to use it very lightly because you can lose alot of detail by mis-using it.
but this wont get the black spots black, no just make a new layer, and zoom in then just go over the spots with the brush- do the same for dust and whatnot with the whites
as for greys, the best way to do this is to make a new layer and RE-DRAW the lines, then make another layer and fill the grey spots with grey
and for straightening panels, go to image>rotate canvas>arbitrary then type in some small number to just play around and see exactly how much you need; often times only a decimal is needed 0.4 or 0.7 etc.
and for coloring, i could explain exactly how i color, but that wouldnt give you a chance to develope your own techniques and styles; just follow the tutorials word for word and tinker with how you do it after you get the basics down
im sure that most of this isnt what you wanted to hear, but thats all there is, no secret techniques, nothin...
[wow omg this is the longest post ive ever typed >_< lol]
