You need to be willing to stretch to more then on medium. Learning Photoshop as pointed out will help you a tone in your chances of getting in. Pick a coloring program: Photoshop / Illistrator / Painter are all great programs that are just another form of a "tool" in your arsinal. A concept artest needs to be able to design and draw more then creatures and horror.
A concept artiest is a master of illustration but in the game industry you need to be more. Can you design rip sheets and Character concepts as well as lvl concepts. Can you give the new guy in the pipe line a feeling of the color for textured as well as massing of the character? Design a site it doesn't need to be flashy it can be vary simple in lay out just do one that is appealing to the eyes and desplays what you do. Make it strait to the point of what you want to do.
I hope this helped you!