2-3 coats of resin on the outside, then fiberglass & resin on the inside.
EDIT: I have use fiberglass on the outside of my Iron Man mask (limited locations), to keep the shape while I fiberglass the inside. Howerever I don't recomend doing this.
From what I've found putting any fiberglass mat on the outside can be done, but it's difficult to get perfect, and really only helpful for adding a bit extra reinforcment on areas before fiberglassing the inside that really may have a warping problem when putting fiberglass inside. Basically what Dizzerak said. Regardless, it's difficult, and you're doing it the correct way.