Place apostrophes where a character is missing. EG:
House o' Glass (not House "o" Glass)
Rock 'n' Roll
Quotation marks are called "sixes and nines" because the opening mark is like a "6" and the closing mark in like a "9". An apostrophe merely looks like an opening single quote. Note that Rock 'n' Roll has apostrophe marks, not single quotes.
It's is the truncation of it is or it has. On the other hand, its is a possessive pronoun similar to his, hers, theirs, and ours.
These are rules set forth by J. Y. Dayananda in 1986 for the USA Plain English campaign.
Prefer the shorter word to the longer one. Use simple, everyday words rather than fancy ones. Prefer verbs over nouns and adjectives. Prefer the specific word to the general.
Write short sentences with an average of no more than 20 words. Use the active voice rather than the passive. Be a miser with compound and complex sentences and a spendthrift with simple sentences.
Write short paragraphs with an average of about 75 words. Avoid paragraphs that exceed five typed line for business letters and ten lines for longer compositions.
Write with the ear. A sentence may look correct on paper but its cadence may be jarring. Listen to your sentences in your head as you write, and do not write anything you could no comfortably say.
Write for the eye as well as the mind. Prepare an overall design, positioning understandable headings, subheadings, and captions for each segment, showing the organization of the text. Make the whole document visually appealing.
Use appropriate underlining, ink colour that contrasts sharply with the paper, lists, boxes or panels, bold or other typefaces to emphasize key points.
Use 'white space' in margins, between sections, paragraphs and lines to make the document look good.