Alright, here's my advice.
For the first one: except for the pattern, your background is pretty dull. Which isn't necessarily a bad thing, just try to have a little bit more going on / around the render. Also, don't have the pattern on the whole thing. I would say to have the pattern faded in parts, but faded out most of it.
Here's what I'm talking about. See how in the upper left, and in the gap between his neck and arm. Just fade it in parts.
Now, that pattern would totally
slaughter your ironman signature. Reason being, your flow is upward, but from
both sides. By that I mean it's going from the right to the upper middle, and from the left it's going to the upper middle as well. The pattern however is only going up and to the right. Hopefully that makes sense.
Your second signature's pretty good. One of the best that I've seen out of you. A few things you could
try if you wanted to. Don't have such a harsh negative lighting. It's like it goes from solid black to signature, no real in between. Unless you're going for an explosion type feel, which I is what I'm seeing.
Another thing you could try, to give it depth. See how his shoulder and face are sharp? Blue his back and opposite shoulder
slightly. It makes it look like your focus is his face and shoulder (which it is). Another thing you can do is mess with the burn and dodge a little, which really brings out the highlights and shadows.
And I know it's beating a dead horse, but yeah your text needs work. The coloring is alright, the brown works but try something more red. Another thing is make sure your text style matches your signature style. For this I could see something eroded or rough. Try this
text from Dafont.com.
If you have any other questions or need example for any of this I can TeamView show you.