This video by Pye from slrlounge takes a look at a simple technique that will help you to use the healing brush and clone stamp tool better.
Most people simply clone the background layer of an image and work on it (it is always better than to work on your original of course). However Pye seems to have another (possibly better) option for you. His suggestion is to use a new blank layer and work on it using the healing brush. All you need to do is to go to the “sample” box and mark use current and below. Notice that this tip actually only works for the healing brush and not the spot healing brush (where you have only the option in the checkbox for “sample all layers” if you wish). The clone stamp can actually do the same thing.
The advantage of this method is that you can very easily see what changes you made by turning off all the other layers and just see the corrections you made and you can use the eraser tool (shortcut E) and erase parts of what you did if you don’t like the specific change you did.
You can find many more Photoshop video tutorials on LensVid’s Photoshop section.