An allusion is a brief suggestive reference to another text, a historical fact, a political event, etc. A general example categorizes or classifies a series. A specific example illustrates the series. An analogy makes a comparison between examples. A definition clarifies a term.
Alternate sentence lengths.
Vary short with longer sentences. Recast your key nouns in different words. Don't let paragraphs go too long. Technical writers advise no longer than 10 sentences and usually not less than 6 or 7. A one-sentence paragraph is appropriate only in specific contexts, such as polemical writing.