And add some texture to it if you really want to go for that realistic look. The thing I'm working on right now is using a couple of textures as well: What I do is I download some photo's from Google, some grass, forest, metal, old paper etc. I copy the layer that has the graphics, paste it, replace the fills with bitmaps. Convert the bitmap layer to a symbol, and lower the alpha. It's a pretty work intensive method but you can make some pretty neat things with it. The benefit of lowering the alpha instead of having just one layer with all different textures is that you can reuse the texture for other materials, you can fade it out more, you can change the color of the fill-layer to achieve totally different effects.
Again if I'm not making any sense... well... I tried.