I can't really help the op with anything that hasn't already been said. I will say though that I prefer to use a really big brush by retouching standards. I find everything goes a lot faster with one. It also helps to skip around the print building the density up as you go. If you try to fix a spot all in one shot it doesn't work very well. By fixing it a little at a time it is very hard to overdo it.

I have found RaphaŽl brushes to be superb. I prefer them over Winsor & Newton anyway.