You have to have someone who can actually see just how difficult something was to make and the nuances of it.
Which has always counted me out. I've rated graphics based on perceptions of visual appeal, based on extensive work in web based design and an interest in graphical design on other mediums (there's a reason I made overlays and basically nothing else for Cricket 07).
I've noticed sometimes my ratings align fairly closely with those who do graphics, but other times varying widely. Perhaps this is mostly to do with me not having the sort of direct graphics making background the rest of you have, but I do feel that I've got enough of a grounding in design to at least not be stabbing in the dark.
Things that I consider key to graphics are: Good colour use, including making use of complementary colours and having a defined foreground and background (and appropriately contrasting these). Using effects to enhance an image not to create the image, effects are supposed to be just that, little bits to add effect, design the overall look first, and then add effects and additional stock to complement it. If the basics of what you are making are ugly, no amount of effects will change that. Maintaining aspect ratios and using readable fonts for text that is supposed to be read, for the first one, make sure never to resize an image without doing so in a consistent way, stretching something in one direction only never looks right, for fonts, make sure to choose sans-serif or serif fonts based on the overall style, likewise avoid those broken up fonts unless they really fit with what you are doing. Some people also add way too much text, sometimes none can be better, and people often underuse the device of using text as a window into a background, it can work really well sometimes.
In short, have a good design plan first and then add things, but less is usually better than more when trying to decide the right amount of effects. Choose your stock and work with it, rather than trying to work around the idea for a background. Do the text last and be cautious with odd looking fonts.
Also, I honestly don't get why on earth you use all the terms for things you guys do. I try to incorporate some of them, but some of the usage of words make no logical sense to me. Think of it as an old person trying to talk like all the young kids do, they might get some of it right, but it is fail on all levels.
In case anyone wonders I personally use Macromedia Fireworks (MX 2004), which was the last good version of it, especially since Adobe bought them. Much more suitable for my needs and much cheaper too. There's the trade off of not doing half the stuff you can do on Photoshop, but haven't found it lacking in normal use.
Also, if you ever want me to give more details on my comments on an entry of yours, send me a VM with a link to you posting it in your thread and mention the specifics of what you wanted more info on. I can't tell you what to do in photoshop to do it better, but I can usually expand on why something isn't right. I can't guarantee I'll respond, but I'll try.