There are a few things you can do to prevent fallout, pretty simple and you might be doing then already. One, tap off your brush for excess shadow before pressing it / tapping it onto your eye, also cover your cheek with a napkin as you blend. If you’re using a glittery or dark or colorful shadow sometimes it’s better to apply your eyes first before getting started on your base makeup. And you can also run your concealer brush or foundation brush over your undereye area to freshen it up and clear out the fallout at the same time. But besides just covering the face? There isn’t much else you can do to prevent fallout, if you’re already using a base for the glitter to adhere to.