doesn't look too good technical-wise.
First two panels have large areas of white, that look like you tried to erase smudges with cg brush, unfortunately large gray spots, and nasty edges ruin the effect.
Jpg compression set to a very high value makes all the lines jadged, and painful for eyes.
Plusses: yup, it's darker allright, and they don't blend with the background as they used to.
scan in high res (at least 300-400 dpi), greyscale.
Then adjust on computer: first apply curves/levels.
Adjust the whites to make all light-gray smudges white and thus invisible.
Adjust the dark part to make the darkest line you can make really black (as in #000000), unless you think you don't need to.
Then use brush to erase all mistakes, and smudges that were too dark to be removed with levels/curves.
You can even do this: take 3 layers: your scan, new layer, curves/levels layer
and spray some white on the new layer, in places where the dark-graysmudges are. Use BIG, and very delicate (say 10% opacity) spray.
It will make dark areas ligh-gray and then curves will finish them up,
but it won't destroy really dark lines- so it won't destroy lineart.
That way if you have a line you wish to keep, and a nasty dark spot you need to get rid of in one place, it's no problem.
THEN merge all the layers, and resize to your desidered size.
remember to merge BEFORE resizing.
and then save it as gif/png.
USE EXPORT/SAVE FOR WEB/or whatever it's called feature, reduce the number of colors to 16 (mediancut) for grayscale comics. You may need more colors if there is some color on the page (ie a blood stain), you're going to have to experiment with it.