What I know about retouching mostly came from trial and error when spotting black and white prints. I still have a set of spotting brushes and a small palette I used to use to mix Spotone for different papers (but the Spotone is long gone). I am slowly putting together all the equipment I need for a working darkroom (and looking for a pace to set it all up), but once I do I have no doubt I will start doing print and negative retouching again. Looking forward to it, in fact. I also did a little hand-coloring but never really got into that.