Knead the dough until it feels smooth and is no longer sticky. Many people liken the texture you're looking for to that of an earlobe or a baby's bottom. Firm and smooth yet yielding and pliant is another way to describe it. Getting the dough to this texture takes 5 to 10 minutes depending on the flour, the humidity in the room, and your strength and speed at kneading.
Cover the dough with plastic wrap and chill it for at least 30 minutes and up to overnight. This resting stage lets the gluten you've developed relax so it won't spring back when you roll it out. It is oh-so-tempting to skip this stage, but resist that urge; the time saved will be spent in the frustrated exercise of trying to get the un-rested (wound up and anxious) dough to relax and do what you want it to do!