when I don't like to use eraser, I make a really dirty sketch and trace with pen. if I don't like the drawing or it's not balanced I trace with pencil and draw it again. it's good to use new paper and trace it, cuz if you rub too much w/ eraser and use maker to color, the ink will bleed
and I don't xerox my work, but I heard it's good to xerox and color it w/ marker.
I try not to make mistake, but if I do... I make it look like a shadow and cover the lines