Adding more detail and making a texture look real takes some effort. The know-how is in a tutorial in this series: Creating a Realistic Head in Blender – part 08 – Clothing Textures. In the 8th of the series, CG Cookie Blender is working on the clothes. So, don’t let the title put you off.
You’ll notice Cycles and the Node Editor are not used in the early creation part. So, it is mostly an older workflow. Still, I found the video helpful on a number of levels.