If you want to learn to shave your head with a DE razor, first you need better blades then the one Walgreen's sell. Get some Feathers (classicshaving.com) or some Derby of Israelis (e-bay). Second it's going to take some time to perfect your technique, first pass with the grain then re-lather and second pass across or against the grain. Third, it's always going to take longer to shave with a DE then a pivoting cartridge razor.
I've been shaving my face for several years with a DE, until 6 months ago I still used the Headblade on my head but I noticed that my headshave wasn't as goos as my face shave and I was purchasing inexpensive DE blades bought in bulk and expensive cartridges bought in pack of 4 & 8. I dedicated myself to learning to shave my head with a DE like Yul did back in the day and now I get a equally great shave on my face and head.