Noise reduction within Luminosity channel

Hello,

I am trying to find information on the best techniques to reduce noise in an image without losing detail which usually happens with most of the automated tools.
I have heard that with manipulation in the Luminosity channel you can obtain really good results, any idea where I can find more information from which I can learn?

I assume it is something tedious like dodge and burn with curves lets say, I just don`t know the correct terms.
I am looking to achieve results which are very polished like in those images.

Thank you in advance and I apologize if my question is not 100 % clear.