An awful lot depends on what type of finish is on the wood. The link below lists some ways you can use to tell what finish you have. You need to scroll down a bit to find the info.

Here is a link that might be useful: how to determine the finish

Start with a sponge or towel dampened with soapy water. Scrub off, wipe dry with a clean towel.

It's hands and knees work, but you should only have to do it once.

Then wax it well with a good paste wax and buff the heck out of it.