Hi @Crashark.  Ahhhh - the dreaded jaggies!   Here is one way:   Work on a good sized canvas and have the black lines and then the color fill, on their own layers.   On the Black lines use Feather. Select the space in between and make a new layer and fill it. Feather the green again and flatten your image.   Also - a PDNers best friend is the AA's Assistant as well.   Voila:       Hope this works for you.