Portrait work with D3000, what lens/settings would work best?

I'm interested in doing portrait work with my D3000 Nikon. I have the 55mm lens and the 55-200mm lens, which is what I shoot with most the time. Looking to see what lens would work best for portraits. Also I'm learning my camera, what settings would produce crisp, clean photos?

What lens is the 55mm? Do you mean the 18-55mm?

Get a 50mm f1.8 - one of Nikon's cheapest but best primes. You'll need to manually focus it on your D3000. Suggest spot metering on the subject to correctly meter skin tones.

For serious portrait work, you'll eventually want to look into some off camera lighting - portable flashes (speedlights) are a good option, when combined with a osftbox or umbrella you can get nice soft lighting from them.

My personal preference for portraiture is to isolate the subject with a shallow depth of field. This means using the largest aperture possible which is the smallest number e.g. F1.8. Neither of those lenses have max apertures that large, but you could use the 55-200 zoomed to around 100mm and using the A (for aperture mode) set to the lowest number aperture, which is probably f4. The distance from your subjetc will allow you to isolate them from the background. Invest in the Nikon 35mm AF-S 1.8. Its only $200 and will work with the D3000.

So much of this depends on the light. If you're in a brightly lit area, you should be able to use a low aperture (maybe set your camera on aperture priority mode) and a fast shutter speed, which will give you a better chance at a sharp image and you'll get a nice, soft background. Zoom your 55-200 as much as possible (anything more than 100mm would be ideal). This will soften the background and compress your subject's features, which is usually more appealing and flattering.