I don't do anything for my peels. I only wash them if they get sauce on them, and then only with hot water and a gentle sponging. Never soak them with water. If you want to add a bit of water resistance, you could use some cutting board oil (a.k.a. mineral oil) to add some protection.
Wood is actually a pretty good bacterial inhibitor. Wood will last a long time - but not forever. We have a pizza peel that is 5 years old and it is used every day. It still is just fine without mineral oil or any other wood pampering.
i use mineral oil, sometimes olive oil if i'm really out of everything else. if you happen to have an Ikea near you, a lifetime supply of mineral oil will cost you a couple bucks. i also clean it immediately after using it, so that nothing sits on the wood too long.