"Conserve"/"Restore"/"Refinish" *LINK*
Bob Smalser, Seabeck, WA
>Great answers below.
When I was doing this, I preferred a minimalist restoration approach....save all the original finish you can because it's historically correct and it saves work.
It's much harder to correct ham-handed, amateur repair/refinish jobs and my link below also addresses that.
Make any mechanical repairs first. I like to leave all marks of honest use but repair the abuse. Your choice how far you go, but I generally leave minor burn marks, ink stains and scratches in. But I have also spliced in new veneer aged/dyed to match the old (difficult) and filled scratches with shellac stick or these days...thick cyano glue.
Then I use a solvent that only removes the deteriorated layer of finish on 0000 steel wool and spread the deteriorated finish onto any new repairs to match the color.
Then I simply topcoat with a compatible finish...lacquer or alkyd varnish....never, ever poly.
My goal is to make the piece appear it is its actual age but has been well-cared-for instead of abused.
Constantines used to make veneer repair punches that did both male and female pieces with a hard-to-see irregular edge. Nice to have, but spendy. But you can duplicate the technique with an Xacto knife and some practice.
Matching new wood to old often requires bleaching the new wood first, then dyeing it as close as you can get, then often coloring the entire topcoat.
Good luck....hope these help you.
Restoring Varnished Hardwood