The next big installment to Mac OS X is 10.9 Mavericks. The big software update is due to be launched later in 2013, having been delayed so Apple can - presumably - finish other projects.
Among other things Mavericks offers better support for multiple monitors; tabs for Mac OS X Finder and better battery life.
Mac OS X 10.9 Mavericks system requirements
The first thing you need to do is to make sure your Mac can run Mavericks. Because the software is currently in development these may change during the run up to the launch.
The current requirements seem to be the same as Mac OS X 10.8 Mountain Lion. This includes all MacBooks Airs released after late 2008, and mid to late 2007 MacBook Pros; plus mid 2009 or later 13 inch MacBook Pros. So if you’ve bought your machine in the last five years you will probably be okay. Be sure to check before you purchase Mac OS X 10.9 Mavericks.
Installing Mavericks: Do a drive check with Disk Utility
Prior to installing the Mac OS X 10.9 Mavericks software you should do a thorough check of your hard drive. Open Applications > Disk Utility and highlight your main hard drive. Now click Verify Disk Permissions and Repair disk Permissions.
Update to Mavericks: Update your software
You should open App Store and click Updates and Update All prior to installing Mavericks. Making sure all software is up-to-date before performing the install will make the post installation process much easier. Sometimes developers include updates just before they launch that improves compatibility with the software. Make sure you perform updates on other key software programs that exists outside of App Store. Especially programs like Microsoft Office and Adobe Creative Suite: these have shown compatability problems in the past.
Back up your Mac before you update to Mavericks
Before you begin to install Mac OS X Mavericks you should make sure to perform a good and solid backup. We generally advise that you do this prior to the next step, even though it’ll take longer: it’ll also help if you delete something you need. It’s probably best to attach a USB hard drive to your Mac and fire up Time Machine to perform the backup; although there are other options out there. But Time Machine’s integration with Mac OS X will come in useful during the update process.
Spring clean just before the install
With your disk checked and all the software updated, now is a great time to do some spring cleaning. Go through and remove any unwanted apps, a program like App Zapper is great for this. Remove unwanted Mail accounts, calendars and unwanted contacts. Delete all your old files that you no longer need and empty the trash.
Check app compatibility
Probably the single most important thing to do prior to installing a new version of Mac OS X is to check the compatibility of your apps. This is especially important if you rely on the machine for work and use key apps like Microsoft Office or Adobe Creative Suite. These aren't always compatible on day one and you may need to wait for an update to them before upgrading to Mac OS X Mavericks.
A website called Roaringapps does a great job of checking app compatibility with Mac OS X software updates. Be sure to check it before performing the update.
Disable File Vault prior to the Mac OS X Mavericks Update
Prior to performing the software update to Mac OS X you should be sure to disable any encryption software like Apple’s File Vault. This will make the update process smoother, and it helps tremendously if there are any errors. You can re-install the encryption software service after the update has completed.