Creating the Shader
Exactly how you create the shader will depend on your software, but if you created the maps using the same reference image, all the maps should be aligned properly. For skin, Blinn shaders work well. If your software supports Oren-Nayer Blinn, then choose that because it has a much softer look, which usually helps when texturing characters. In a pinch, a Phong shader will also work, as will many other types.
Place the color, bump, and specularity maps in the appropriate slots. Set the color map to 100%, and adjust the strength of the other maps until the surface looks right.