There is noticeable color fringing in these pictures,(not your fault)but only a photographer such as my self would really notice.
First one is very nice,just needs some post processing done.
framing is way off in the second one.considering that it just a blue sky and a cactus to the side.There is alot of dead space in the picture.
Third one,not sure what your point of focus was.Im going to guess the cat,in that case, hes out of the frame a little bit.But the image its self,is sharp as hell bro,good job on that.
forth one......i have mixed emotions about it.i dont like portrait shots that much, if you back up,and got more of the structure in frame as well,it would've came out interesting.
All and All,it looks like you are just getting in to photography,which is fucking fantastic.
but as expected,you dont really know all of the tips and trick around photography.
I can give lessons over PM if you would be interested.(free of course)
~Swyne