The same principles used for cleaning/polishing any piece of finished wood apply (check around on the internet) with a few more likely. You'll need to determine what your finish is or, at the very least, how your finishes react to various cleaners/chemicals. Always test a
small out of the way area first. Some finishes will not melt/dissolve under most conditions - others easily start doing so (like shellac) and can we reworked nicely if you are prepared to do so. My bench usually includes various oils (do not discount WD-40), lacquer thinner, denatured alcohol, mineral spirits, and of course Old English. Different parts of the stock may need verious treatments especially around the action. As a final step, a bees wax polish may be in order - I use Birchwood Casey Stock Polish myself. Hopefully you don't have one finished with epoxy like I did - had to start over with that one.