I think you'll need to to practice more the observation skill.
Some of your texture doesn't look that realistic because it miss something (maybe the specular, maybe the glossiness, or a kind of "structure and storytelling").
If you want to work in game, it's better to provide them all in-engine or real-time (UDK, CryEngine 3 SDK, Xoliul sahder, etc...).
At least, racer445 put an awesome tutorial on texturing props & stuffs so you can learn more about!
http://www.nextgenhardsurface.com/index ... d=racer445
Good luck!
