First order of business: delete iTunes from your computer and replace it with something better.
I basically ignore genre because I don't find it that useful and it's too much of a hassle to add to every track (by album wouldn't work in most cases due to the eclectic nature of VGM).
Composer tags for composers, 'artist' for arrangers or prominent performers/vocalists as JQM said. I'll usually add all the performers with their own tags and roles (don't remember if iTunes even lets you add new ones like this). For album artist I'll typically include all composers unless someone had an absolutely minuscule role with only one track or something. I only like to use 'various artists' for massive compilations like
this one.