OK, they are not hard and fast, without exception, never to be violated rules. But follow them if you want your publication to look professional, be easy to read, and reflect well on you.
Also see the Fonts.
Everything you learned in your high school typing class no longer applies.
Punctuation
Alignment
Paragraphs
Dashes
Quotes & Apostrophes
Caps
Underlined
Line Width
Justified vs. Ragged Right
Flush Left & Centered