Well , there's much I like here and much I don't.
The Katich wallpaper has some excellent bits together with some ordinary ones. I really like the way the subject is blended in with the clouds and the overall effect it gives. But beyond this I think all other background work is really unnecessary. Maybe some paper textures to give it a bit of grungy touch but that's it. Text is too close together. Also the border around Simon doesn't come off well.
The Album cover is cool and retro looking. Again some work would have made it even better, but there's not much to fault with here. Maybe that line-brush stroke on the right should have been a touch darker, it's a bit distracting from the main thing.
The sig is looking good, but should have been better. I guess it will appeal to most, but I think the subject should really standout more. The colour combination could have been better too. Matt, I suggest when you start with the first texture/ background, you give it a colour gradient. Just decide the primary color you would like your sig to be and choose an appropriate gradient. It will give depth to the image.
Overall I think you are still doing pretty good really!
Hope that helps mate and keep it up!