I am using Photoshop Elements. This is the image I'm starting with (Artbook scan from Manga Style):


1. Remove Color Cast

The first thing I usually do is Remove Color Cast. This picture wasn't that bad, but some of the artbook images or anime screen caps change a LOT when you use this tool. It works by asking you to select a part of the image that should be white, black, or grey. I usually go with white. Then, it edits the image's color in order for that particular spot to turn out white, black, or grey like it should be.  

2. Surface Blur

I use this to clear up the image. It somewhat blurs the texture, as opposed to a Gaussian Blur which blurs the entire image. If you're having trouble seeing what changed, look closely at the top left area of the picture.

3. Adjust Sharpness

This makes the image much sharper and makes up for the blur that you just added to the picture. In this image, you can especially see the difference if you look at face.

4. Adjust Levels

I pretty much just toyed around with the sliders until it looked good. You can especially tell the difference when looking at the blue on her fuku.

*EXTRA*
5. Brightness & Contrast

I just barely tweaked the Brightness & Contrast. This isn't really one of the routine things that I do, but I just thought it would make this particular image look better.

Before and After:

Even though each step didn't seem like much, in the end, the image looks MUCH clearer!

Image from Mangastyle.net
This is the image I am starting off with:


I love the Filter: Noise - Reduce Noise on or around these settings:

This is what it looks like afterwards:



Then I love to make my things more vibrant:


Here is what that makes it look like:


Lastly for this image I'll play with the Levels:


Here is the final product:


The last image is to show a comparison, pretty sure you can tell which part is the original:


Lastly, I find that Naoko's images tend to be on the yellow side, especially when you try to play with the vibrancy and saturation. I would suggest going to hue and saturation, choosing the "yellow" option or part and lightening it. It helps a whole lot.