I do pretty much all my art in plain old MS Paint. It's what I've used since I was a little kid and I pretty much never stopped. When I'm done with a drawing I stick it in GIMP to get a transparent background and then select the dark outline, use Select > Grow, grow it by 3 px, and then fill in the selection with white on a background layer. While this is specific to GIMP, lots of art programs have tools to let you manipulate a selected area, so I'm sure an equivalent trick could be found on SAI, PS, etc etc. And as many do, when I'm done, I host my images in Imgur. I hope this gives some insight!