It looks like you have a decent bit of potential and you're really looking to get better so I'll start CnCing your work.
I'm going to only CnC the top one because your second sig has the same flaws.
So, reference image.
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Let me start off by saying this; you're going about making sigs the wrong way. What I'm seeing right now is you putting a render onto a background and then adding effect C4Ds over and under the render. This is an improper way to go about sigs. Since you're only using effect C4Ds, your background is left completely "raw" and it sticks out a lot and looks extremely flat. Your background should not take up a majority of the tag, perhaps about 10% of it maybe (it really depends on what your render looks good with). What makes up the other 90% of the tag you say? Well, your render should take up a good bit, and your C4Ds should be taking up the rest. NOT your effect C4Ds, but your regular C4Ds that you should be adding behind AND in front of the render (add in front of the render in areas that don't take away from the focal.) Then after that you can add effects such as effect C4Ds (although I don't like how those look in general so I usually go with some bubble C4Ds or some space/nebula stocks).
This image is how a good tag looks when it has the credentials like I described above.
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Notice how there's barely any of the actual background layer showing.
It's important when looking at this step to make sure you do what looks good rather than sticking to only 10% on every tag.
For example, on the tag below, I left much more than 10% of the background layer showing. I did this because I thought the tag would be too dark overall if I put more C4Ds on the bottom left and also I liked what I did instead because that really blurred out C4D gave my tag a lot more depth.
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Now, there's other things to keep in mind. Things such as flow, lighting, placement, depth, and text. I'm not going to go through each thing individually with you on this tag because that's a lot to write out. But if you haven't already, read my
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on signature making.
You seem to have general knowledge of text. Since I didn't do the text section well in my tutorial I'll skim over it a bit here. You're doing some good things, but you chose bad fonts. Choose fonts that fit the atmosphere better, and don't use drop shadows, they make the text look tacky. I'd suggest learning how to use stroke well because that's what makes text look good in my opinion.
Well I was about to CnC, but I am too tired now after reading Pavoneo's CnC lol. In all honesty though there really isn't anything else to say, P covered it pretty good imo KIU