Quick tip: I've had some sealers and glazes react poorly to one another. Always let the layer underneath dry THOROUGHLY. Test the combination first. I wouldn't want you to get the cloudy blue thing that happened on one of my jewelry boxes going on with one of your customs!
I use the glaze on top, and don't use a sealer, but the stuff I use is also rated for use as a sealer/topcoat, so obviously there's not going to be a problem there.