This isn't a new technique, however it might spark an idea for you to use.
The first thing I did was choose a neutral background and fixed, double sided tape in a rough outline of the sticker I was using.
I cut her out close to the lines. Next I mounted the sticker under a 'transfer tape' This allows for an easy positioning and release. You can see by the tiny pieces, some were left behind on the sticker. Don't worry, you can transfer them with craft tweezers after.
I centered her over the tape background and pressed her down.
Working from darkest to lightest color I carefully removed the sticker body and filled in the exposed tape areas with glitter.
It is helpful to work from the bottom up.
Once I had it glittered to my taste. I then cut her very close to the edge and mounted her on my layout.