i noticed that you make your sigs way to long in width and way to short in height .. maybe use 400x150 or 380x120 ..
this sig is good but the lighting source is to far away from her, that gives the sig two focals .. you wanna keep your focal the render
so what you can do is, have the lighting come from behind her right shoulder
i think that would look better, and also the colors are VERY boring, you gotta use more strong lively colors .. you can do two things with the colors on this sig
1. you could try to have some more color techniques, color balance, photo filter etc. and try to choose 1 main color you want for your sig , blue would match good on this sig ... so you can bring in some more colors in this sig
2. you can add more contrast and have it black and white , i think that would look VERY good, especially when you altered the lighting source to behind her shoulders .. the black and white would also eliminate most of the plain left side of the sig, giving the render more focal
also one last improved you could make on this sig is the text
set up the "to sin666" under the "Allure"
cause now everyone has to focus between the two texts
if you could make a v2 with the advice i have giving you, I'm sure v2 would look better
anyways, good job

it's totally not bad