If you want to fake lens flare in an image, drag a layer of blurred-out lights on top of your photograph (they will appear just like blurs or highlights from the bokeh of a lens). Then, change the blend mode of the blurred lights layer in the Layers panel to Overlay, Soft Light, or Hard Light. The type of blend mode will depend on the underlying image and the desired effect.
Tip by: Lindsay Adler -- www.lindsayadlerphotography.com
Photoshop User Magazine -- 13th Annual Top 100 Photoshop Tips -- Pg 47
To start, the only touch-up I did was on the eyes to ease the red-eye effect in the pupils. I'm not sure if I could explain it, but the Red-Eye Tool in earlier versions seemed to be much more effective than in CS6. To compensate, I spent a couple minutes using brushes and masks to get us to this:
I won't show all the variations I played with, as I did in the previous tutorial. Instead, I've chosen to display just one of the blurred lights in all three blend modes.
The thumbnails don't do much to exemplify the differences, but a closer inspection of each (or better yet, your own experiments) will help you get a better idea of which blend mode, and why.