Greetings! The 18-70 Nikkor sold in kit form is a fairly decent lens. Scott mentioned the lens sharpness was subpar, however, for portraiture, especially closeups, the softness in the image may be to your advantage and liking. Besides, the price is reasonable and wont break the bank. If cost is no object, try the 17-55 F2.8 AF-S zoom Nikkor. Sharp, contrasty, fast, heavy, expensive and uses the 77mm filter thread. There's also the 85mm F1.4 that's really for portraiture and very likely the lens you'd use for a head & shoulders portrait. This lens has been around for a while so you may be able to pick up a decent slightly used one for far less than new. This photo was taken with the 18-70 zoom Nikkor kit lens
This one with the 85mm F1.4 Nikkor AI-S Manual lens