Also leave a single space between sentences. Punctuation - End every sentence with a single punctuation mark immediately after the last word. For most sentences, use a period. If the sentence is a question, use a question mark. Only occasionally, when you wish to add strong emphasis to a sentence, use an exclamation point.
Exclamation points tend to be overused.
If you use them very often, they lose their effect. It is not necessary to use multiple exclamation points or question marks at the end of a single sentence. Sometimes this is done to add even more emphasis, but it is rarely effective. Use commas as short pauses between parts of a sentence, or to separate items in a list within a sentence. Apostrophes are a little tricky, but worth mastering.