Might as well add a pinch of CnC
You're not optomizing your depth, you have the concept down of achieving it, but you're forgetting to properly blur your C4Ds so it looks a bit more flat than it should be. (I recommend .6-1.3px gaussian blurring for C4Ds)
Biggest problem with your tag: It's too monotone so people are getting put off from looking at the tag and it's a bit difficult to look at and take in. Your render seems to have some brown/red in there, so make your C4Ds have a bit of brown/red in there as well. Monotone tags are generally ugly.
You're not really putting any proper lighting in your tag either. The render is calling for a yellowish/greenish light source on the right side of the tag, and a hint of a light source on the upper left (you can tell from the left clothing fur thing) but you didn't put any light source indication in the tag at all (unless you count the C4Ds, then there's some improper lighting in the tag). Work on some central lighting.
Small note; more often than not, you don't want a pure black background to work with. Import a wallpaper or background and just blur it out a lot. This makes the tag more vibrant and possibly gives the tag more colours so it doesn't look as monotone.