Nikon D3100 new lens?

I'm ready to upgrade from my started lens what lens would you say I should buy next between $200-300
Best for portrait & landscape

You should get a Nikon 18-105mm lens.

http://www.ebay.com/...0620230599

It will be really good for Portraits and Landscapes.
If you do not want or need VR (Vibration Reduction)
You could get the Nikon 18-70mm lens for way cheaper.

http://www.ebay.com/...0802754265

If you are not using a tripod get the Nikon 18-105mm lens.
The 18-70mm lens does not have VR, so you should use a tripod.
If you do not want to use a tripod get the Nikon 18-105mm lens.
If you do not care to use a tripod and want to save some money get the Nikon 18-70mm lens.
The 18-105mm lens may be better for portraits because it has more focal length.
People do not like there picture taken with a camera right in there face.
That is where the extra focal length will become handy.

18-105mm f3.5-5.6 VR Nikon lens is right in your price range and it a great lens.

18mm is good enough for landscapes. 55mm is great for close-up portraits. 35mm is good for people, pets and general shooting. If you have the 18-55mm kit lens, that's exactly what you need.

If you like making distant subjects appear closer to you, get a telephoto lens like the 55-250mm or the 70-300mm. If you want easier background blurring abilities for close-ups, get the 50mm f/1.8. If you want that same background blurring power for more applications, get the 35mm f/1.8.

You are not gaining much for $200 to $300 over what you already have if you want to do portraits and landscapes.

For the best landscapes, you want to go something less than 18mm, say like the Tokina 11-16mm (but it's $650).

And the best portrait lens is still an 85mm prime, regardless of whether or not you have a cropped camera. The blurry background capable with this lens can't be matched by a 35mm or 50mm lens.

Many people with your camera opt for the 55-200mm or 55-300mm lens as their second lens; which would be in your budget. But this is more of a wildlife and nature lens than for landscapes.