Now that you’ve gone through all the preliminary steps, it’s time to begin the upgrade. For most people, Plan A—essentially letting the installer do what it wants to do—is the logical choice. And remember, if it doesn’t work out for any reason, you can always move on later to Upgrade Using Plan B: Clean Install. Nevertheless, because you may encounter some questions or confusion during the process, I detail exactly what steps to take from start to finish.
Unlike Mac OS X installers of old, the Mavericks installer requires no separate startup disc; you simply run an application and it does its thing. However, if you haven’t already done so: