Hmmm, well, let's see here...

Some of my favorite effects:
-I like to copy the layer (or entire blend), put it as a new layer on top and set to "Screen" and desaturate a little (or a lot). Then duplicate this layer and set it to "Soft Light". Play around with the opacity and saturation of both layers
-Use lots of textures

Good layer modes to put them on are Overlay, Soft Light, Multiply, and Lighten.
-Use sparkly brushes in white and set to overlay.
-Curves and Selective Color layers are THE BEST for adding color!

(this will only work on Photoshop, I believe

)
Some of my favorite sites for brushes and textures are:
The Magic Box,
Hybrid Genesis,
Gender,
Ewanism,
77 Words, and
Maquina
Also, if you see a particular effect you like, just ask the artist
