Now that you know which basic technique you’re going to use, you’re nearly ready to proceed. Your next step (which could take hours, or even longer) is to obtain the Mountain Lion installer; then I’ll recommend a few other quick, last-minute tasks before you dive in.
Depending on your situation, obtaining the Mountain Lion installer may be a trivial matter of a few clicks, or it may be an involved ordeal. Let’s start with the easiest case first.
If you’re running 10.6.8 or later and have a broadband Internet connection that can handle a 4+ GB download, obtaining Mountain Lion is easy—it’s just like buying any other app:
1.Click the App Store icon in your Dock, click ...