I add some Pearl Ex, less than 1/8th of a teaspoon is fine, but it depends on how sparkly you want it, a bit of glue, and water. I've noticed that I need to add more than a "drop" of glue like the tutorials on youtube say, but it's all good. I used it on two little pieces of this card here
Ponies and Crafts: Waste Not Want Not Wednesdays. I like to add some distress inks along with my powders to give them an extra kick. You can also buy much cheaper mini misters off ebay if you go searching for small perfume sprayers.