Watch the video in fullscreen to see the details.
1 - Apply the plugin to your clip.
2 - Add a color mask.
3 - Select the skin using the eyedropper.
4 - Click and drag to select an area. Hold Shift while clicking to add to previous selection. Hold Option while clicking to subtract.
5 - Adjust the Skin.Smoothing and Smoothing.Mix settings in the Inspector. Remember that subtlety is key. Overdoing it will result in undesirable results.