Not too bad shorty COuld use a few adjustments however.

First of the contrast on this tag is a bit high up. So if you added a levels or a curves or soemthign in this sig, lower it's opacity so the contrast is more nuetral.

the colors need a bit of work. i reccomend using hue/saturations, color balances and gradient maps (on low opacities and blending modes) to create a more balanced color scheme. right now there are a ton of colors everywhere, if you minimize them more they will be more relative ot eachother and look less chaotic. Watch out you don't make it monotone though.

The BG is not bad at all. the right side has coole ffects, that nbeam of light isnt bad, and the c4d is pretty cool> overall it leads to pretty good flow and bg.
However you need to try and blend the render into it a bit more. try overlapping the BG and effects onto the render a bit more so it feels more like one.

Also i dont know if this was part of the stock but those circles in the backgorund really kill the flow. I'd try to get rid of them if you can.

In signatures liek these it's always gard to mix a vector-like object with other 3 dimensional looking objects. It just makes it tough. I reccomend trying to use different focals like videogame characters and other thigns, they might be easier for you.

It's all about experimenting.
In the meantime maybe try out a few signature tutorials, to get your bearings a bit more.