These are just some general suggestions to make your manga coloring as pleasing to the eye as possible.
Cropping - I suggest you pay attention to what and where you crop. More then likely you are taking a small portion of a whole page when you color. When you do this, try to make sure that no random lines from other panels on the page are in yours. Or more likely than not, your panel may over lap with another. Decide to either include both panels, or if you may need to cut off part of what you are coloring.
Negative Space: ( Definition: Negative space, in art, is the space around and between the subject(s) of an image.) It’s dramatic, draws attention to the parts you really want, and personally I think it looks great when you want a larger canvas. See above for an example of a panel that I made into one with negative space.
2/3rds Rule: This is a little more advanced than cropping and draws upon both the suggestions above to make it work. The 2/3rds rule means that the object in the photo only takes up 2/3s of the frame, and is typically not the center of the image. For an example of what I mean, then click here. So if you crop an image that does not end at the end of the page, aka like her hair in the example link, then add on to the white space to make the frame follow this rule. It’s much more pleasing to the eye, as proven by photographers around the world.
Cleaning a manga scan means you are removing screen tones, removing parts of the scan where you can see the grain of the paper from when it was scanned, or taking out unwanted words, items, etc. I’ll be honest when I say it’s the hardest, most boring and time consuming part of manga coloring.
This is actually really easy to do, as it can even be done in paint.
Start your scan in one layer and make a second layer underneath it.
Make this bottom layer white.
Now erase the parts on the scan layer you don’t want, either using the eraser, or a lasso tool for faster larger more defined section.
Simply color over the parts you don’t want in your image with white (or black in some cases)
This can be done in paint, however it’s recommended that if you use this method try to use something that allows you to have layers to work with.
Why do this you might ask? Well, personally, I feel that when coloring images, figuring out how to color screentone is the most difficult part of coloring.If if overlaps with other parts of my coloring it’s even hard to deal with, in the end it generally makes your stuff look much better.
Tip #1 - Always color your background! You can see the difference between the two photos in the example. If you follow my “method two”, found on my FAQ, when it comes to manga coloring, then this should be very easy!