The Exclamation Point
Nothing makes you look like an amateur — or an idiot — faster than using too many exclamation points.
Exclamation points are like profanity. They are our special little friends who should only be trotted out every once in a great while. Use them too often, and they lose their impact. Use them where they don’t belong, and you look coarse or childish.
If you must use an exclamation point, use it sparingly; never employ it more than once per document. (There are always exceptions, of course. There is no rule of writing I have not deliberately broken for emphasis or to make some other point.) You can get away with using such punctuation conversationally more easily than when you’re writing for business (or in communication with people who are not your friends).
Remember, too, that using multiple exclamation points after the same word doesn’t give your sentence more impact. It makes you look like an imbecile, a fourteen-year-old, or both.