OS X Mavericks

I have recently learned that there is a free upgrade from OS X Mountain Lion to OS X Mavericks.
http://www.apple.com/osx/

I have never upgraded an operating system in a MacBook Air before.

I have tons of experience in updating MS DOS and MS Windows.

This website offers some analogy and rationality for me as new convert to Mac OS from MS Windows:

How to creat a bootable OS X Mavericks USB

http://howto.cnet.com/8301-11310_39-57608836-285/how-to-create-a-bootable-os-x-mavericks-usb-install-drive/

Creating an OS X USB installer from the App Store download hasn't been very straightforward in the past, and the old methods no longer work for OS X 10.9. However, there's a new Apple utility with Mavericks that makes it relatively simple, and thanks to MacForums member, tywebb13, we know how to use it. With a USB installer, you'll be able to perform a clean installation ofMavericks whenever you want and without having to download it again from the App Store. Here's how to create a bootable OS X Mavericks install drive: (kindly proceed to the website from CNET for the steps)

http://howto.cnet.com/8301-11310_39-57608836-285/how-to-create-a-bootable-os-x-mavericks-usb-install-drive/

Wish me luck as I will try this over the weekend.  I only installed minimal very few programmes in my new MacBook Air.  (I just installed open office and updated Adobe flash for Safari).  I am not entirely sure if I should do a clean install of mavericks...