By the way, if you do want to keep the glitter flat, my trick is to apply it carefully in small areas with a fine brush. You will have to clean (and blot dry) between every application, otherwise it will become gummed up with the wet varnish which you will pick up in laying the gloss down. Glitter is static-y so it will cling lightly to a dry brush.
I also used a toothpick to pick off errant bits of glitter.