For comics, you normally work in cmyk mode as it is in that mode that your work will be printed. Have your monitor well calibrated!
In case it's for your own fun or home print, you can use rgb.
For more info on brushes etc, you can either use the help, or do a search. Many tutorials are available.
right.
now to the technique:
-First make your drawing on paper and evt. trace it in ink.
-Then you scan it.
-Set it to cmyk mode and go to the channels palette.
-Duplicate the K channel and enhance the contrast with levels.
-Load this channel as a selection, and invert.
-On a new layer, and with foreground clour set to black, press Alt+Del to fill the selection with black. Now you have a fully transparant layer with your black outline on.
-Now you can easily select each cell, give it its own layer and paint it. You can evt use blur limited to the cell/selection to get smoother effects. The idea is that you place these layers below your black outline layer, just like in the final printed result.
as said: if it's for print, paint in cmyk mode. if it's for home use or the net, you can change to rgb after having created the black outline layer.