Best Practices before doing any Mac OS System Upgrade

Best practices before doing any Mac OS upgrade: 

0) Read the info on compatibility with your software:

OS X: About incompatible software - http://support.apple.com/kb/HT3258?viewlocale=en_US

1) Always backup your data. 

Make a good and complete backup with Time Machine and/or make a copy of your disk with Disk Utility.

How to back up and restore your files - http://support.apple.com/kb/HT1553
Time Machine 101 - http://support.apple.com/kb/HT1427

2) Understand how to restore your backup (you did make that backup!) before you start.

How to back up and restore your files - http://support.apple.com/kb/HT1553

3) Make sure that all software updates have been completed before upgrading.

4) Repair the startup disk with Disk Utility before upgrading and after upgrading.

Download the latest OS X install application from the App Store or from Software@NCState and install.