Before you update to Final Cut Pro X 10.0.8
Apple has updated Final Cut Pro X to version 10.0.8 in the App store but before you update to this latest version,
Apple recommends that you back up your current Projects, Events and the FCPX app itself.
Apple recommends that you back up the Final Cut Pro app by zipping it and placing the zipped file in a new folder.
Right click on the Final Cut Pro app in your Applications folder and choose Compress Final Cut Pro.
Make a new folder named Final Cut Pro 10.0.7 and place the zipped app inside.
Apple's Final Cut Pro X: Best practices for updating support article is located here.
Place backup copies of Events and Projects inside of a new backup folder so Final Cut Pro X 10.0.8 doesn't open the backed up versions.
I back up my CurrentVersion.fcpevent and CurrentVersion.fcpproject files on a regular basis anyway but especially before updating to a new version of Final cut Pro.
10.0.8 is the second maintenance update/bug fix update for Final Cut Pro X in a row. 10.0.7 was also a maintenence/bug fix update. We haven't had any new features added since 10.0.6 back on October 23rd, over 5 months ago.
Features have been added to FCPX in only 3 updates according to Apple:
Final Cut Pro X version 10.0.6 adds the following features:
Final Cut Pro X version 10.0.3 adds the following features:
Final Cut Pro X version 10.0.1 adds the following features:
Final Cut Pro X version 10.0.8
This update improves overall stability, performance, and compatibility.