Your best bet is to do what, Sithslayer78, said. During glassing, if I get an air bubble, I just pat it down with the paint brush that has resin on it. Typically, a good way to not get air bubbles, is to paint the resin onto the strip of fiberglass, then carefully place it inside the piece you're glassing. Lay it on like a sticker, when you're trying to not let any air bubbles get trapped under it. If there is an air bubble, you could use a paint brush to sort of push the air bubble to the edge of the fiberglass then flatten the fiberglass there.