That George Eads is not too bad at all. I would not have known you had to paste around the Doc's head had you not said so. Sometimes with a manip you can smudge the background layer around the head, but with that one I think the cut and paste route was better. As for George, you might try reducing the brightness some more on his face so he blends better with the background.
Don't worry about the first collar on Triple H being purple hon--maybe he's in the diplomatic corps! (can you imagine him being a diplomat?

). A good way to recolor, if you're using Photoshop, is to select the area around the collar and put it on a new layer, then got to Images>Adjustmetns>Desaturate. Then select the color you want from the color palette and change your Brush Tool to the Color Replacement tool and paint over the collar. Then go to Images>Adjustments>Hue/Saturation and fiddle 'til satisfied. Oh, and you may also wish to adjust Brightness and contrast, too.
Don't be afraid to check out the Resources and Tutorials section for tips on how to do manips. I've found more than one of them really helpful, and I've even posted a few myself (like the one I described above). And if you're using Gimp, don't fret---
Mad-Martigan has posted some Gimp tutorials there as well.
Keep up the good work and don't be afraid to experiment!