Open the Image in Photoshop

This tutorial should work in most (if not all) versions of Photoshop. For this tutorial I will be using Adobe Photoshop CS4. Open (Ctrl + O) the Image you would like to modify.

I’ll be using this image of leaves that are being lit up by the sun.

Duplicate the Original

It’s good to duplicate the original image, and leave it sitting there just in case you need it later. Make it a habit. To duplicate it, right click on the layer and select “Duplicate Layer…”.

Play with the Levels

Next up, we will change the levels. You use Levels to correct or adjust the tonal range and color balance of an image by adjusting intensity levels of image shadows, midtones, and highlights.

Drag the black, gray, and white arrows around until you are pleased with the outcome. The black arrow controls the shadows, the gray arrow controls the midtones, and the white arrow controls the highlights.
Try not to overdo it.

Make it POP!

Now it’s time to make this photo look great. Duplicate the layer you changed the levels on. Your layers palette should now look similar to this.

Next, do a Gaussian Blur on your new layer. Go to Filter > Blur > Gaussian Blur.

Make the Image look blurry. A Radius of somewhere around 5 pixels should do the job, depending on the size of your photo.

Now set your Layer Mode to Soft Light, and give the layer an Opacity of around 40-80%.

Final Result
Quite a transformation. More advanced users should consider using Curves, Color Balance, and cropping the photo, for a better effect.