Photoshop light effect

Step 1: Open a new document, I used 800x600 pixels and look for a model photo on the internet, this is the one I used:

After downloading, place it on your document. Now we will start to retouch it!
Step 2: As you can see, it is a bit dark so we should make it brighter first. Duplicate your photo by pressing Ctrl-J and change its blending mode to Screen. Simple, right?

 It is now better. Merge down this layer donw by pressing Ctrl-E. After that, duplicate it again and go to Filter>Blur>Gaussian Blur and use a value of 4.5 pixels

Step 3: Change the blending mode to Overlay and merge it down. The model now looks wonderful!

 Step 4: Next we will add some light on her. Use the Pen tool and make some point around the dark areas of the model, don't need to be so exact

 Step 5: Convert this path into a selected area, you can save this area for later use by going to Select>Save Selection

Step 6: Create a new layer and go to Filter>Render>Clouds and Filter>Artistic>Plastic Wrap, just use the default values

Now change its blending mode to Color Dodge. Your photo may look a bit different:

Step 7: In the next steps, we will add light effect on the model. Use the Pen tool to draw some curves on her

 

Step 8: Reset your colors by pressing D and invert them by pressing X. Choose the Brush tool and go to Window>Brushes to open the Brushes panel. Pick a small brush (about 5 pixels) with 0% hardness and tick on Shape Dynamics. Create a new layer, choose the Pen tool again, right click and choose Stroke Path. Make sure you tick on the Simulate Pressure before pressing OK

A small curve, thinner at two ends appear like this:

Step 9: Repeat step 8 again but this time we also tick on the Scattering checkbox (make sure you make it on a new layer)

After choosing Stroke Path, we get

Now we can delete the path by pressing Enter. Double click on your two new created layers to open Layer Style dialog box. Use Outer Glow as following:

Use the Eraser tool to delete some light areas, the glowing light seems to surround her. After this step, we get:

Step 10: Make our light effect stronger by duplicate the "glowing dots" layer. Press Ctrl-I to invert its colors

Change the blending mode to Overlay. And this is the result: