A search on "Penis Shaving" leads to a number of good sites. One by a group called the "Nudist Nudist" (they do shave all their body hair below the neck) in particular has a lot of good ideas.

I don't always, but when I have shaved my pubic area, I've sometimes used scissors to trim the area close first, thn a good razor with very careful strokes. I have nicked a few times, but not bad.