Hi all - I recently purchased a 15 year old pine table and chairs. It's stained and has a rustic look, which I love, but I think I should probably do something to protect it from from grease/water stains. I do not want to ruin the rustic look and do not want anything shiny looking. Should I just sand it lightly and then put a couple of coats of polyurethane on it? Should I use matte/flat or satin finish? Any other suggestions? Thank you!