This document discusses principles for improving writing flow, including eliminating wordiness, being concrete rather than abstract, and matching subjects and agents of verbs. It defines flow as incorporating logic, organization and style at the sentence level. Some tips for improving flow are removing unnecessary words, using specific verbs and adjectives instead of abstract nouns, and ensuring the subject of a verb is the agent performing the action. Examples are provided to illustrate concise versus wordy writing and concrete versus abstract terms. The document is the first part of an online writing course on flow.