Imo stronglifts is just some guy changing Rippetoes SS program around. They pretty much admit it. There is some decent information on that site I guess but why not just go to the source?
The book Starting Strength goes into tons of detail on the overhead barbell press. He has a DVD out as well that is filled with videos of him correcting common mistakes in the basic barbell exercises.
You can find a ton of information on proper form on the SS wiki.
Military Press
Press Video Page
Starting Strength Wiki