The rules for exclamation points in publishing are simple. If it is at all possible, show excitement, emphasis, or extra emotion with words. I often edit manuscripts inundated with exclamation points, and if you are trying to get your book published, that's a big no-no. Acquisition editors will see your overuse of the exclamation point as inexperience.
So when should you use an exclamation point? If used sparingly, the exclamation point can add extra emphasis. For example, take this tag line.
"I don't know where it goes."
That seems like a simple, declaratory statement. If you want to show frustration or anger you can use the exclamation point.
"I don't know where it goes!"
However, here's another big no-no.
"I don't know where it goes!" Laura shouted.
The way this is written, it says that Laura makes her statement, and then she shouts--additionally after speaking.
In any case, use the exclamation point sparingly, and instead, as your kindergarten teacher told you, 'Use your words.'