[Rizo]

I would recommend checking the Gnomon Workshop DVDSs, they were awesome learning tools when I decided to become a Concept Artist. Videos from Feng Zhu will teach you perspective and composition, later they are other great vids from James Clyne, Ryan Church, and Dylan Cole.
After that is just a matter of painting as much as you can until your work start getting a professional look, post in forums, and take all the feedback you can. Good luck!