After HR I stayed on for three months as part of their Hacker in Residence program. During that time I prepared and delivered lectures on various algorithms and data structures, which was great preparation for whiteboard interviews.

I also planned for the Google interview to be relatively late in my job hunt. I already had offers in hand and a lot of on-site practice going into it. I doubt I would have passed had it been my first on-site engineering interview.

Beyond that nothing special. A lot of CTCI stuff and daily practice.

that sounds like excellent strategy. i will follow this path.

The Google interview process is tough, but it is predictable.

You know exactly what they are going to question you on(algorithms), so it is straightforward to prepare for (which is not the same as "easy")