For starters, you need to make sure you and your Mac have what it takes to handle Mavericks—specifically:
A Mac that’s not a geezer. Mavericks can run on any Mac that Mountain Lion could. That list includes the iMac (mid-2007 or newer), aluminum MacBook (late 2008 or newer), plastic MacBook (early 2009 or newer), MacBook Pro (mid-2007 or newer), MacBook Air (late 2008 or newer), Mac mini (early 2009 or newer), or Mac Pro (early 2008 or newer).
Some features, like AirDrop, Power Nap, and AirPlay mirroring, work only on more recent models.
Snow Leopard or later. Your Mac has to be running OS X 10.6.8 or later (Snow Leopard, Lion, or Mountain Lion). Even if you have one of those, run Software Update to make sure you have the latest version of that edition.
Free storage space. You need at least 8 GB free on your hard drive or flash storage to install Mac OS X 10.9. More is much better.
A lot of memory. Apple recommends at least 2 GB of memory, but OS X absolutely loves memory. For the greatest speed, install 4 gigabytes—more if you can afford it. (And these days, you probably can.)
The latest firmware. Firmware describes the low-level, underlying software instructions that control the actual circuitry of your Mac. Every now and then, Apple updates it for certain Mac models, and it’s very important that your Mac have the absolute latest. If yours doesn’t, a message will appear to let you know during the installation. Quit the installer and grab the latest update from ...