Since it's going to be outside, it's a good idea to stain or paint the wood, to protect it from the elements. Mine is under an overhang, but I still stained it to match the front deck. It's also a good idea to line the numbers with a contrasting paint color. Just a thin line will suffice to make the numbers stand out in the daylight. I had the paint already, but a cheap bottle of craft paint can be purchased for just a few dollars. Again, put some effort into it, you're going to be looking at it every day, and telling people to look for it.