For long exposures
try your camera’s ‘long exposure’ or ‘dark frame subtraction’ noise reduction. This should remove almost all noise with no reduction in quality. The downside is it will double your exposure time.

Useful photography plugins for Photoshop and Lightroom
Kevin Kubota’s Digital Fill Flash action,
Kevin’s Smokeless Burn to lighten and darken specific areas of my images
Kevin Kubota’s X-process combo action at about 18%, used magic sharp (also Kevin Kubota) for sharpening
link: http://kubotaimagetools.com/