Just don't make it look new. I worked on 18th century mahogany and walnut, using 10X steel wool very lightly. Hopefully what you have is an old stock from the 40s, 50s, or 60s. They can come up nicely with a cleaning and removal of a portion of old finish and reapplication. Never use stripper. I have even used tung oil, so lots of things on the market work, even in conjunction with an old finish, including the TruOil already mentioned. The boiled linseed is really a classic finish, but does take a long time to dry between coats. "Once a week for a month, once a month for a year, once a year for the rest of your life" was an old saying. Be gentle. You hear of people scraping a finish with a piece of broken glass! Don't!