Sharpness nikon d200?

Should i keep the sharpness at +2 on the nikon d200

Take some shots at 0, 1, 2 etc. And at various ISOs. Then pic the level for the ISO that you like best.
Personally, I like to shoot RAW and sharpen the image myself. If I was shooting a JPEG, I would keep the sharpening at 0 too, unless I was being lazy and just wanted some quick snapshots without any editing. However, the problem with setting the sharpening in camera is that the sharpening gets applied to the entire image. This is bad because you don't need to sharpen the entire image all the time, and doing so will increase the visibility of noise. For example, the sky portion of a landscape doesn't have any detail to sharpen - it's just a swath of blue. Applying in-camera sharpening will sharpen these textureless areas, producing noise. This is why I would prefer to leave the camera at 0, and do the sharpening in Lightroom or Photoshop where I can apply a mask to only sharpen those areas that need it.
On the other hand, if I was shooting a party inside, for example, then I'd probably use some sharpening so that I wouldn't have to do it in post. That's where doing the test of various levels of sharpness with various ISO settings comes in handy.

There's a reason for turning down sharpness and contrast in-camera. Turned up, the images straight from the camera look more snappy, and turned down more dull. But the duller images provide more latitude for software adjustment. Trying to unsharpen or decrease contrast afterwards, there will be sharpening artifacts and narrowed dynamic range that can't really be undone.

To each his own taste.