All the things Just L commented on plus some cnc of mine:
About the sig as a whole thing: Pretty good for your skills but i would recommend y to watch more tutorials!
About the depth:there is mere depth here,you should work on it!(sharpening the render once
and blurring some parts of the bg a little works fine for now..)
About the sharpening:Carfull in how y sharpen cause as y can see his shoulders have a dot like effect(i dont know how to pronnounce it) as y sharpened the render a lot!Avoid the oversharpening!
About the blending:Y tried to blend the render with the help of the white brush(?) around him but it just doesnt make it as y imagined it...(only in his head we can see a good effect as y have made a light source from above!)Practice with blend tuts as they can help y hide a lot of mistakes(e.x. oversharpening)
About the bg:I can see some C4d here but y paste above them blue gradient..not good...try to add more c4d next time and dont make it so small,try to cover the bg with them but dont forget that y mustnt overdo it!Stocks like these tribunal effect pics~~~>dont use them again!(It just makes your sig Low quality)
About the flow:It hasnt exactly..!Try to make the bg move the same direction as your render!So it have a solid flow for now!(Later y will learn other techniques but that works for now)~~~
About the text:Nice font,but
dont ever,and i say ever use this kind of glow in text!Kill it with firexDIt just ruins your sig!My advice is that you can start making sigs without text for now and then when y will be making solid good sigs add a text,cause it only ruins your sigs more now...
Overall...Nice job,keep improving!The sig has lots of flows but thats inexperience!
P.S:If you want i can send y some tuts..