Siri dictation (speech to text) for emails and text messages is by far the quickest and easiest way to input text on the iPhone. Just tap the microphone button to the left of the space bar on the iPhone keyboard. And these tricks will make it even easier.
First, you can name pretty much any punctuation character to add it: period, question mark, exclamation point, comma, colon, dash, close paren, ellipsis…
You can also insert returns by saying new line, or start a new paragraph by saying new paragraph.
And Siri knows a few emoticons too: smiley, frowny, and winky.
But please only use these (and dictation in general) when you are alone. Don't be that jerk.