Hey welcome to climb-x.
i gotta say pretty nice for some of ur firsts.
On all of them i think they are too big maybe make the canvas size smaller, if u do this you will find it easier to fill the sig.
1st one - always try to centerize the render. txt is ok
2nd - render is mutch better imo its well blended and the bg brushing is nice.
3rd - i would try andwork on the txt a little.

make sure you check out some of the really good sig tuts in the tutorial section, they will help ALOT! they helped me lol