OK.. Not all lost, I've often seen guitars that have overdosed on TLC. The owners are meticulous, after playing they wipe the guitar down with a duster. And they regularly apply brand name guitar polishes.
What actually happens is that they spread the sweat and oils very evenly over the guitar and then apply a layer of polish over the top to seal it in.
So, top of the list is to get rid of all the crap that has built up over the years and get back to the factory finish. And the best way to do this is to get a bottle of White Spirit and a fresh kitchen roll. White Spirit is perfectly safe on all guitar finishes, it is almost certainly used in the factory to clean up before, during and after spraying.
It will strip all the grease and dirt away and leave you with the original finish.
Buff up with an ordinary yellow duster.
If you really want to use a polish, apply now. But never forget the basic rule, Clean 1st, THEN polish. Otherwise, all you are doing is smearing the dirt and grease around evenly and then sealing in with the polish.
Hope that helps.
When you see a fork in the road, take it.