I think the exclamation point is the worst punctuation mark. I use it rarely, if ever. I cannot find a natural way to use it in informative writing.
According to the recommendations, an exclamation mark can end a sentence that expresses enthusiasm or strong feeling (I’m so happy!). The history of the exclamation mark supports such use; the mark itself is believed to have developed from the Latin word io, ’hurray’. Copyists wrote this at the end of joyful sentences. Through the centuries the word transformed into a symbol, with the former letter I above and the O becoming a small circle. In a way, the exclamation mark was a kind of medieval smiley.
You may also use the exclamation mark after an interjection (Ouch!), in salutations (Dear Customers!) and in wishes (Happy Easter!). Even in these cases, I prefer a period because the exclamation point seems a bit too strong, almost like capital letters – and the mere idea of that combination is SIMPLY TOO MUCH!
So I think that one recommendation about the exclamation point is enough: don’t use it.