I spend a non-trivial amount of time shaving my own head. (Or persuading others to do it for me; I'm not terribly particular and it's a wonderful way to make friends. Particularly if you pay them, which to be honest is how I make most of my non-shaving-my-head friends anyway.) In order to maximize efficiency and shaving pleasure I've experimented with a variety of shaving contrivances, and my findings indicate that using the edge of a bladed weapon--a katana, a machete, one of those Crocodile Dundee knives--is no more effective than simply relying on a Mach 5 Turbo. They do, however, make me feel like more of a man, a task which surpasses the head-shaving itself in both importance and level of difficulty.
I've also investigated the efficacy of many different creams, lotions, and lubricants for facilitating the shaving process. I tend to alternate between baby oil and Cool Whip. The problem, however, is that these are so much fun to apply to my head (or other parts of my body; again, I'm not terribly particular and it's a wonderful way to make friends) that I frequently forgo the actual shaving for which the application of said products was intended and simply walk around the apartment, or the sections of the apartment I'm allowed to be in unsupervised, with baby oil or Cool Whip on my head.
This has led to several other discoveries. For example, you'd be surprised how well a bald head dipped in oil works as a ski slope for your snow-themed G.I. Joe action figures. Also, maintaining a supply of maraschino cherries to place atop the Cool Whip makes me feel like a farmer. A delicious farmer.