You can have more control over your retouching by using blank layers.
Blank layers are transparent.
They have no pixels, just a white-and-gray checkerboard pattern.
The retouching goes on a blank layer, not on the Background copy layer.
Let's call the blank layer, Layer 1.
To make a Layer 1, select the Background copy layer (usually).
Click the Create a new layer icon at the top of the Layers palette.
Layer 1 appears above the Background copy layer.
By placing the retouching on a Layer 1, you can do the following.
You can reduce the opacity of Layer 1 to reduce the effect of the retouching that's on the layer.
Reducing the opacity allows some of the unretouched Background copy layer to be visible.
The mixture of unretouched and retouched can create a more realistic result.
You can erase a portion of the retouching on Layer 1 by using the Eraser tool.
If it's a mess, delete Layer 1 and start over.
You can change the retouching on Layer 1 with an adjustment layer.
1) Create a Levels adjustment layer or Hue/Saturation adjustment layer above Layer 1.
2) Group the adjustment layer with Layer 1.
If you haven't already done so, go to Grouping.
When grouped, the adjustment layer will only affect the retouching on Layer 1.
You can paint a mask with the Brush tool, with black, to block the effect of the adjustment layer, from part of Layer 1.