I'm going to walk through, complete with screenshots, my installing Lubuntu 14.04 LTS, a modified distribution of Ubuntu Linux that uses the lightweight LXDE desktop environment and OpenBox window manager.
The last time I installed a fresh copy of Ubuntu was probably when I wrote up Installing Windows 7 & Ubuntu UNR side-by-side on Dell Mini more than four years ago. Before that, I installed Ubuntu on a desktop, which I upgraded to Lubuntu by installing the required packages but without uninstalling any of the Unity shell items from Ubuntu.
With the new LTS release of Lubuntu, I felt it's ready for conservative users like myself to install. LTS means it has three years of long term support, which means I don't have to do any major upgrades for at least that long (of course, normal minor upgrades from week to week is still necessary).
A fresh install gives us a chance to clear out the cobwebs, idle packages that were installed but is no longer needed by us, etc. It also gives us a chance to install it with full disk encryption (FDE), which was available before, but didn't seem quite ready for prime time for conservative users.