There's a few ways:
The main way is to use it with a 212, and then just pat it on under my lower lashes. I use it that way with the Reflects glitters. I also sometimes use it very carefully as a top liner with a 209.
Another way I use it is I will use a little bit of a glitter like Reflects Gold in the crease, applied with a brush like a 231. You want to use a brush like that, as it is denser, so it will not get as much glitter trapped in the brush.
For some more festive looks, I will use a little bit of glitter mixed with a lighter pigment like Jardin Aires, with some Helium (Vanilla would be a good one in this bunch too) and then use it as a thing to put over blush. I have a few batches of mixed pigment and this is a good one-but you have to go light on the glitter. You can also use a blush brush with a teensy bit in order to get a nice look.
For the lips, I have a bunch of disposable lip brushes, and what I will do is brush a bit of glitter on top of a lipglass.
Of course they are also nice to use for more costume-y looks. My halloween look was a mask and I got a good amount of use out of Gold, 3D Silver, Reflects Gold, and so forth.
On a separate note, if you love pigments, you need Silver Fog. I find that I like the pearl finish pigments a lot more than the frosts, because the pearl-form is denser and less chunky, I get more colour saturation, and I can create some interesting looks with it. Golden Lemon, unfortunately, is now a pro-only...however, it is a very chunky pigment. Great colour, but not so easy to work with.