In this tutorial I will show you a perfect way to enhance the skin of a girl with some layer and filter effects

First get the image you want to work with, in this tutorial I used the one below:

Step 1: Open the file with Photoshop, first we need to increase the contrast of this image a bit with the Levels tool (go to Image>Adjustments>Levels). Notice that there are 3 sliders in this tool, moving the black slider to the right will increase the darkness of dark areas and moving the white slider to the left will increase the brightness of bright areas. So, to make this image more contrast, simply moving the black slider to the right and the white slider to the left a bit.

Our image will look like this:

Step 2: Next go to Filter>Blur>Surface Bur to make her skin smoother with these parameters. Don't try to use big values with this tool because it will make our image unnatural

Step 3: Press Ctrl-J to duplicate this layer (the Background). In this step we will apply the Diffuse Glow filter to our image. To do this go to Filter>Distort>Diffuse Glow and use these settings:

Notice that after clicking OK you will see many white dots on her skin, especially on the white areas

Step 4: Now go to Filter>Blur>Gaussian Blur and use below settings to make these white dots blurrer

Step 5: In the Layers tab, change the Blending mode of this layer to Soft Light to blend these 2 layers

Now we will have a wonderful photo and it looks very professional!

Just compare with the initial photo, you will realize it was enhanced a lot

This method can be applied to retouch many images in the real world and it's rather easy to do. Hope you enjoy this tutorial!