When to use noise reduction in DPP (1 Viewer)

As each week goes by I learn a little more about processing my images. On the image below of the Red Kite I was able to lift the shadows on the
underside of the wings which improved the image including being a bit more confident in the rest of the processing in DPP and Adobe 6 Elements.

At the moment I suppose like most people I adjust the image to my eyes until I am happy with what I have done. But when it comes to the noise reduction
in DPP I really don't know what to do, but I have been applying 7 or 8 Luminance and 7 to 8 Chrominance am I doing right.

I use neat image and apply it after sharpening in my workflow. Others do it before.

I don't fiddle too much with the luminance

I try not to exceed 2 in luminance NR and 4 in chrominance. If you have more noise in your image, using a dedicated NR program like NeatImage will provide better results.

NR is best applied before cropping and sharpening the image.

I do not do any NR in DPP, preferring to use Noise Ninja (or NI) from CS2. Like Marcus, I also run NR after sharpening - a lot of people do it before, personal preference really. The reason I do it after sharpening is that NR destroys detail and if you do it before sharpening you have less detail to work with. The downside to this is that sharpening will enhance any noise that is there.
When I do apply noise reduction I always use a mask so the NR will only apply to the areas I want (mainly the BG and not the bird).
Like I say, it is personal preference and there is no absolutely right or wrong way.