I'm relatively new to the restores too. Before I joined this site, just over a year ago, I had done a few bits and bobs that I downloaded from Google images to practice on and a few of my own.
I had been using GIMP and various bits of software from here and there for many years, but primarily on modern photos to improve or manipulate into fun pics. I still do quite a bit in this area.
So.....whilst I thank Mike for his kind comment, Its a bit 'blind leading the blind'
The main comment I'd make at this stage, is that I very rarely use the auto type filters except for the occasional bit of de-noising and even then I tend to have the strength turned down as they often make more work than they solve. For light scratches I would use the healing tool and for heavier stuff I would use the clone at various opacities and then probably go over it again with the healing tool. Its a long drawn out process and does take a lot of time.
To repair a badly damaged eye, I will more often than not clone the good eye from a flipped version.
Some of the more experienced restorers, I'm not really happy to single anyone out, but Yvonne, Cazz and Carol are extremely clever artists and can show most of us the way home, studying their work should be recommended to anyone taking up this hobby. Some of their jobs can be quite understated, but its not until you have a bash yourself that you realise just how smart they are.
I do work with layers quite bit (obviously for the colouring...but) mainly because not all areas of a pic require the same treatment, especially over or under exposed bits, so I will work on the separate areas as transparent layers and then flatten the image later.
And Mike, as you brought up the music, both you and I are musicians and there is only one way! As a young muso, I once asked a visiting musician how he had done a certain riff during his show, his one word answer was, "Practice"........ at the time, I thought him an arrogant chuff, but of course he was absolutely right