Alright, work has been hell so I haven't been around.
The Disturbed pic (The blended one): It was a nice choice of colors, though I feel like the render felt stretched. I know it's a weird image so it might be that. (I've made a signature with that pic and it came out in the same way.) The blend is nice, but it's almost too blended. What you might want to try is taking a grunge brush to the background to show some distinction between the render and the background.
The Carnage signature: I like the font of the text in the first one more than the second, though you should try blending it more (try dropping the opacity of it to 70-80%). On the other hand, the text in the second version has better placement, though it still seems a little high. I'd also make it smaller. Personally, I like texts that don't have too much to them. Let the picture be exciting, and the text be more of a compliment than anything else. In the second, I liked the C4D but I think you should've erased some of it. It covers way too much of the render; especially the piece that goes over his face and through his mouth. It also sticks out like a sore thumb because of how plain (?) the red is compared to the rest which is a mixture of red and black. Try putting photo filters or gradient maps over the top of your completed signature to tie them all together. Personally, I almost always drop the saturation some right before adding two or three gradient maps to give it all the same tint. It's a trick that helps with blending.
The weird wet looking thing with the teeth: I really like this one. The darkness on the edges is a nice touch, though I don't think I would've went in so deep with it. And if you are going to go that deep in the corners, the edges around the rest of the signature should have some too. Same note on the text, it's generally a no-no to have the text on the render. It should be on the smaller side and right near the render to drag the eye to it. If it's over it, your focus ends up on the text more than the render.
The Anime Signature: At first, it looks good. It has a nice flow in the foreground, but then when you focus on the background you can see that other C4D you added which goes in the total opposite direction and throws things off. And just like in the carnage one, the pieces that land up near his face make the render harder to read. The text I would've gone smaller, and this may be a personal thing but strokes and outlines on text very rarely look good especially when that thick. I made a signature about an hour ago that just would not work with text unless I put a stroke around it, so sometimes it's needed but even then it shouldn't be more than one pixel. I also wouldn't spread your name out that far. I like to get the letters to almost touch when I stack it like that. It's a good placement otherwise, though.
Ghost Rider: First thing I notice is the text. You have a lot of room on the right hand of the signature so there's really no reason it needs to be on the render the way it is. I don't know if it was the render, or the way you resized it but it looks smooshed. In photoshop, when resizing, if you hold shift it will keep the size ratio so that doesn't happen. Blending would've helped in this one. Again, saturation and gradient maps work wonders when it comes to unifying a signature.
You've come a long way from the first one you posted so I wouldn't get discouraged. I would look at some signatures (whether it be from designers here or other sites like shadowplay is irrelevant) just to get a general feel of what the goal is when making one. The difference doesn't really hit you until you see it first hand.
These are two I made a long time ago, and a fair distance apart. You can see how I just haphazardly tossed the C4D behind Shao Khan, but then I started looking more closely and taking the time to erase and re-add different parts of C4Ds to create a flow like in the sonic one (And even that one isn't all that wonderful). It's all trial and error, and practice. Keep up with the tutorials and you'll continue to get better. I can say from personal experience that I hate tutorials but the minute I stopped doing them I stopped growing. I still do, and re-do them. Today, actually, I did the "Complete beginners tutorial" I sent you just to brush up on some things I had stopped doing (like messing with the dodge and burn tools).
