The easiest way to make the transition to Linux, in my case, was setting up a dual boot system with Windows and Ubuntu where the Windows system simply didn't get to be booted anymore.
A friend of mine, who is a full-blown Linux geek, kept nagging me about giving Linux a try.
Back then my only experience with Linux was an awfully configured, unstable Linux Linpus that had come with my netbook as an OEM install.
Since the Linpus distro on my netbook was pretty much useless and had only caused me problems so far, I gave him leave to install some other flavour of Linux and show me how it all worked in the process.
That way he taught me some Linux basics, including stuff like how to use a terminal (my friend is an avid fan of the command line, and I guess so am I now, too), file systems, the OSI model, the Free Software movement, and so on.
The positive experience with Linux on my netbook eventually inspired me to have Linux running on my desktop computer, too.
This is how the dual-boot system came into being.
After the setup it so happened that I booted only Ubuntu for several days straight, and somehow, there didn't seem to be a real reason for me to go back to using Windows.
Ubuntu was very easy to use, almost hassle-free (at least much more than Windows had ever been), and I had started to like it.
So I just stuck with Linux, and Windows has since been converted to a gaming-only system :)
My friend is always at my disposal whenever I encounter a problem, and I also consult Linux-specific sites or forums on the Internet for that purpose frequently.
So, my transition to Linux happened more or less instantly and I am still by no means an expert, but I try to learn as much as I can.
It does take some time, though, and sometimes the best solution for a problem eludes me until after having gained more insight and knowledge somewhere else.
At the moment, I am trying out Linux from Scratch (LFS) because I feel that I still know too little about the inner workings of my Linux system.
LFS does not really count as a Linux distribution, but is rather a detailed step-by-step manual for building your own Linux system from scratch (hence the name) and learning which gears make which part of the system run.
Perhaps you might want to give this a shot, too?