Oh my God !!! Please, please, please don't ever use the Gausian blur on skin in photoshop.
The tools you might use in the Tools Palette:
-blur tool - looks like a rain drop
-rubber stamp tool/Clone tool
#1 what are you trying to smooth out?
If you want to soften the skin up a little bit use the blur tool on a low strenght.
If you want to remove pimples, discoloration, scars, ect.. use the rubber stamp tool.
Check out the source below, it's pretty good.
Before you start, click on the image in the layers pallete.
Drag it to the little icon on the bottom of the pallete that looks like a piece of paper(on left side of trashcan). Then release the mouse button. This will create a copy of your image. Use the copy to work off of. You don't want to mess around with your original image.
Just remember to play with the tool strenght(Opacity) so the newly changed area doesn't look choppy or unnatural.Use the blur tool mentioned above to soften up any rough edges.