Let’s make a more extreme example of the slightly worn shellac, based on this reference photo:
There is dirt on the surface of the object, so add that to the Diffuse map. The color of the wood itself is a bit less intense and somewhat faded.
Increase the contrast for the Reflection map and add some of the details from modifier Diffuse (the lighter spots should be less reflective, so invert those layers as you copy them above Reflect map).
Adjust the Glossiness map by darkening it, to make it more high contrast. The goal is to create patchier, blurrier reflections.
Adjust the Bump map to have more dents and scratches and less wood grain.
Here is the final render.
