Hi, I'm assuming your light units are overhead? If so, you'll want to definitely add front and side lighting options otherwise your portraits will have unflattering shadows. Natural light is the most flattering for portrait work. However, since this isn't always dependable, you'll probably want to pick up some studio lights (with diffusers and umbrellas). Here's a link to an article which addresses portrait photography. You might find some tips you can use in it.
http://www.stnphotography.com/tips.html#lighting