keep working on them m8, you seem to make them a little darker than what they should be use a brightness/contrast to improve on that.
You have the idea of how it all works, you just need to work on your delivery and you need to focus on visual interest. On both tags I see your render, text, and effects, but what else? Visual interest is what makes people say "WOW." If you know what I mean, just practice on lighting and color first, then try making sigs that have more detail and effects that have a point.
I like the first one Imo, I think you should leave it as it is. I'm not so sure about the second one though, the C4D looks out of place =\
well its ok though i dont like the color :/ Try changing how you placed the C4D in the second , 1st is ok but 2nd is kinda strange...