Good Portrait Lens for Nikon?

I need a good portrait lens for a Nikon D3000. Something someone would use for a senior photo shoot or along those lines? I mean rather affordable, under $700 preferably. I already have a Nikon 55-300mm f/4.5-5.6G ED VR lens and the basic 18-55mm f/3.5-5.6G VR lens. Any suggestions?

The lens most used by portrait photographers who have cameras with the same size sensor as your D3000 use the AF-S 50 mm f/1.8 or f/1.4.

Until you can save your pennies, just use the 55-300 mm at 55 mm @ f/4.5 (wide open)

You have some great options!

35mm f/1.8G, 50mm f/1.8G and 50mm f/1.4G. All below $700, my personal favorite would be the 50mm f/1.8G!

Here's a Nikon Portrait Lens Guide - http://www.the-dslr-photographer.com/2011/11/buying-a-portrait-lens-nikon/

Why don't you try the Nikkor 50mm 1.8 AF?

Its as cheap as chips, and when bolted onto the d300 it acts as a 75mm which is great for portraits.
The wide aperture makes for extra blurry backgrounds, too.