Step 15: Select the Sparkle Brush

Switch back over to your Brushes palette, click once again on the words "Brush Presets" in the top left corner of the palette if the option isn't already selected, then scroll all the way down to the bottom of the list of preset brushes on the right. Your "Sparkle Brush" (or whatever you named it) will appear at the bottom:

Step 16: Select The "Shape Dynamics" Option

Click directly on the words Shape Dynamics on the left of the Brushes palette to select the "Shape Dynamics" options, which will appear on the right of the palette. Make sure you click directly on the words and don't just click inside the checkbox on the left:

Step 17: Set The "Size Control" To "Fade"

With "Shape Dynamics" selected, if you look in the top right of the Brushes palette, you'll see a "Size Jitter" option, and directly below that, you'll see a Control option. This "Control" option is technically the "Size Control" option and it allows us to specify what, if anything, will affect the size of the brush as we paint with it. Click on the down-pointing arrow and choose Fade from the list, then enter 25 in the box beside it:

By setting the Size Control option to "Fade", Photoshop will gradually fade the diameter of our brush down to zero when we paint a brush stroke, and it will do so using the number of "steps" we've specified, which in this case is 25. You'll most likely need to experiment with the number of steps to get your sparkle trail to fade out properly with your image, but 25 is a good place to start.

Step 18: Select The "Scattering" Option

Click directly on the words Scattering on the left of the Brushes palette, below the words "Shape Dynamics", to bring up the "Scattering" options. Again, make sure you click directly on the words and don't just click inside the checkbox on the left. We want the "Scattering" options to appear on the right of the Brushes palette and for that, we need to click directly on the words:

Step 19: Set The Scattering Options

When the Scattering options appear on the right of the Brushes palette, enter 110% for the Scatter Amount, then enter 3 for the Count option and 35% for the Count Jitter:

Once again, you'll most likely find you need to experiment with these values a little, since your image will be different.

Step 20: Set The Brush "Spacing" To 50%

Click directly on the words Brush Tip Shape in the top left of the Brushes palette, below the words "Brush Presets". Then, down near the bottom of the Brushes palette, set the Spacing option to about 50%:

In this case, the "Spacing" option determines the maximum length of our brush stroke (our "sparkle trail"), and as with the "Shape Dynamics" and "Scattering" options, some experimenting may be necessary to get your sparkle trail to the proper length for your image.