Open up Adobe Photoshop and make a new document. Using the Text tool, make any sort of writing. I suggest using a font that's thick. I'd suggest using fonts such as Creampuff, Casual, Pt Banana Split, Juice, Impact, etc. [Screenshot]
Go to Layer >> Rasterize >> Type. Now go to Filter >> Noise >> Add Noise. These are the settings I use, you can change it around to suit your preferences. [Screenshot]
Go to Layer >> New >> Layer. You will need some sparkling brushes. I suggest using at0mica.net's Glitz or Sparkles brush (page 2). Add sparkles here and there on the text on this new layer. [Screenshot]
Save the file as glitter1.gif. Trash the layer with the Sparkles on it. Make a new layer. Add sparkles here and there on the text, in different places than you did before. Afterwards, save the file as glitter2.gif. Repeat this process and save the file has glitter3.gif.
This is my glitter: [Screenshot]
Now, you're going to need to download an animation program. I use Microsoft Gif Animator, it's free and easy to use. Click here to download.
After you installed the program, go to File >> New. Animation Wizard will pop up. You can set the seconds to as many as you like, but one second or under is best for glitters. Also, check 'Loop Forever.'

After clicking 'Next,' choose 'Add Image.' Add glitter1.gif, glitter2.gif, and glitter3.gif. You can click the play button to see what your glitter will look like. Go to File >> Save As to complete your glitter!