This effect goes by all sorts of names in the world of Photoshop: soft glow, soft focus, dreamy effect, glamor effect, etc. Whatever you might call it, here's my version of a subtle / barely there soft focus effect.
- Open your image in Photoshop. Remove any dust or distracting elements. Apply any necessary Curves adjustments.
- Duplicate the background layer. Apply a Gaussian Blur of 10 px (you might need more or less, depending on the image quality).
- Duplicate the blurred layer so you have two blurred layers.
- Change the bottom layer's blending mode to Soft Light with layer opacity of 30%.
- Change the top layer's blending mode to Normal with a layer opacity of 30%. This is where I stopped for the flower photo.
- People images look best when features we expect to be sharp and in focus (eyes, eyebrows, lips, etc) are sharp. So, on the top blurred layer, add a layer mask. Using a soft paintbrush, paint with black to reveal the areas you'd like to be sharp. For this photo, since the little girl's bangs were so close to her eyes, I made portions of her bangs sharp too.
- If any areas of the photo are too dark, apply a Curves adjustment.