As always, John B and Proptop have covered the subject pretty well. But since part of the purpose of these forums is to share information, here goes:

A really long time ago, I worked part time for a major prop maker that had made props since 1949. All of his props were machined from maple, which is a very hard wood with generally good grain structure. But because wood is a natural product, there is some variation in the grain. So when you get a nice shiny wood prop, you want to do more than check the balance and reaming the hub to fit the crankshaft (which is important, because forcing the prop on when it almost fits can cause it to fail at the hub).

You want to hold the prop at the hub and one blade, while flexing the other blade. On a 10" or 11" prop, you should be able to flex the tip about 1/4". Check both blades the same way. 99 percent of the time, the blades will just flex and you are good to go. But every once in a while a blade will break, and breaking it in your hands is far better than throwing a blade when you are running it up on your engine.