When you use a magic selection tool, such as the Magic Wand tool, too much may be selected.
You can use the Selection Brush tool to "mop" the excess away.
Be sure to check off as you go along.
First, you can make the selected area stand out.
1) Select the Selection Brush tool.
2) Switch the Mode in the options bar to Mask.
The selected area remains normally colored.
The area that's not selected turns red.
This is called an overlay.
You can change the color in the Overlay Color box.
Increase the Overlay Opacity to make what's selected stand out even more.
You can use the overlay feature of the Selection Brush tool when you're using any of the selection tools.
Now you can mop away what's not needed from the selection with the Selection Brush tool.
1) Make sure the Add to selection button, in the options bar, is selected.
What you do next depends on whether the overlay is being used.
If you're using the overlay, do the following.
2) If the red mask is on, click, hold, and drag the Selection Brush tool brush on the selected areas that need to be deselected.
As you paint, the unneeded areas will change from "clear" to red.
3) Switch Mode in the options bar back to Selection from Mask.
If you're not using the overlay, do the following.
2) If you turned the red mask off by changing Mode from Mask to Selection, do the following.
Press and hold Alt, and click, hold, and drag the brush on the selected areas that need to be deselected.
Pressing and holding Alt makes the Selection Brush tool subtract from the selection.