I shoot fashion.
I never use an external flash on my camera. It is not flattering to the model or the clothing and jewelry ... period
The D60 is an excellent camera in the hands of a competent photographer, so don't get hung up on not having a D3x.
One of my colleagues has been using a D70s for years when shooting fashion professionally and only recently bought a D300. He still uses the D70s when shooting outdoors using flash (multiple heads with light modifiers, not on the camera) because of its higher flash sync feature.
So, my guess is you have a 18-55 mm VR lens. If you buy either the Nikon 24-70 mm f/2.8 or 70-200 mm f/2.8, you will be well on your way to having a fashion system. Which lens you choose will depend upon what kind of fashion shooting you do. If you are shooting on location or in a studio (set), the 24-70 mm f/2.8 is the lens for you. If you mostly shoot runway shows, then you will need the 70-200 mm f/2.8. Neither are inexpensive, but valuable tools for the fashion photographer ... just choose the one that makes most sense now and buy the other one next.
What kind of lighting have you been using? Studio flash or continuous lamps?