For a newbie doing these the only thing i can say looking at them is,the ideas are great,yet on a couple the diffusion needs to be less imo and the render on vidic could do with a more of a blending vanishing point into the background where you have got him coming out from it,lastly the render and text on kaka sig needs slight adjusting on text to make more readable,and render a sharper cutting.
but if that is self cutting not bad as cutting can be differcult to do.

like i said to wiggy though m8,you as the artist need to be happy if you are happy then 9/10 people will more than likely enjoy your work........
The thing is PS you are always learning like myself,so just play about with settings,levels etc;
but for first timer they are good my first wasnt that great but they will become better m8 with pratice..