I record the narrator (AT 4050 large condenser mic) directly to a track in Vegas, chop and cut to tighten and remove mistakes, then gate-EQ-compress (Vegas EQ and Waves R-Vox). A limiter (Waves L2) also goes on the output to compress the narration and music.
two ways of doing this. I use the Lexicon Alpha USB interface with a four channel mixer and an AKG SE300B sm condenser mic you can use the mic of your choice. Then you can record directly to a track.
Or you can write your VO use your mic pluged into your camera- if you use a condenser make sure you have your 48p turned on or have an external power 48 supply. Record to tape and capture the audio and lay it to a track and edit.
Good luck