What can i use to get my dog to realize no means no?

It won'r hurt her if it gets in her face. The shock of being in her nose might make her "sneeze" but she won't die or anything. If the water is supposed to mean, "no" then squirt her butt. that makes her turn around to investigate what hit her, and she turns from whatever she was focused on. Pair the squirt with an unintelligible noise (ahh-uhhhh), and she will definitely think twice before acting out.