This is a work in progress of a cover a did lately. I can't find the inks, but you can see how's my process.
1- I do a quick sketch digitally, to have a general idea of balance and composition. You can see that here I change and adjust what i don't like ( Spidey's head and Iron man in particular). I don't like to go further with details.
2- MISSED FILE- I ink traditionally the cover, after I printed the sketch in blue. Here I add details and put some blacks.
3- I paint in grayscale the whole cover. This is the funniest part of the game! Lights and shadows are set here....now I've just to...
4-...COLOR! I color OVER the gray and add all the "special effects" I want.
Usually the whole process asks 8/10 hours, even if it could ask 2 days if you want to give a more "painted" feeling to the drawing. But you do what you've to do, right?
***UPDATE: Ink version added! ;) Found it!