First and foremost, ensure that your Mac is compatible. You’ll want to have enough RAM (not just the minimum 2 GB, far better to go with more if you can), and ideally (we recomend) at least a 7200 RPM hard drive, better still – ideally – an SSD drive for the best responsiveness.
The listed requirements are as follows (see http://www.apple.com/osx/specs/ ):
“OS X v10.6.8 or later, 2GB of memory , 8GB of available space”
You’ll need an Apple ID if you don’t already have one (and you probably do if you’re using iTunes), see
The compatible hardware/model list is:
“iMac (Mid 2007 or newer)
MacBook (Late 2008 Aluminum, or Early 2009 or newer)
MacBook Pro (Mid/Late 2007 or newer)
Xserve (Early 2009)”
Please – whatever you do – make sure you have a known-good, full backup (via Time Machine or your other backup method of choice) before you do anything.
It’s a good idea to read a little more about it, and Macworld has a great writeup here: