If you want to avoid stripping and refinishing the woodwork in your home, try cleaning it first. Sometimes all it needs is a good scrubbing!
For painted surfaces: Simply scrub with soap and warm water.
For Clear Finishes: Mix equal parts paint thinner and a mild soap, like Murphy Oil Soap. Apply to the area with a sponge or paint brush. Wipe the Solution off with a clean rag to remove the dirt. You might remove a thin layer of varnish or shellac, since the grime may have melded with it.

For the details in the wood: Use a toothbrush to get in there and scrub!
For painted surfaces: Simply scrub with soap and warm water.
For Clear Finishes: Mix equal parts paint thinner and a mild soap, like Murphy Oil Soap. Apply to the area with a sponge or paint brush. Wipe the Solution off with a clean rag to remove the dirt. You might remove a thin layer of varnish or shellac, since the grime may have melded with it.
For the details in the wood: Use a toothbrush to get in there and scrub!