This document discusses several issues to avoid in formal writing, including using informal words, repetitive words, sentences with confused meanings, inappropriate idioms, and incorrect punctuation. It provides examples of more formal alternatives for words like "wanna", "gonna", and "don't". It also gives examples of replacing very repetitive words with synonyms to enrich vocabulary. Issues with squinting modifiers and incorrect comma usage in sentences are explained, along with examples to clarify proper grammar rules. The document advises sticking to formal writing styles and avoiding informal idioms, jargon or vague language in academic essays.