Editing is easier when it happens in passes. First check purpose and structure: does the document contain the right information in the right order? Then improve sentences: make actors and actions visible, remove repetition, and replace abstract phrases with direct words. Proofread only after the meaning is stable.
Concise does not mean abrupt or incomplete. Keep the context, qualification, and courtesy the reader needs; remove words that repeat, delay, or obscure them. Read from the reader's position and ask whether each sentence helps them understand, decide, or act.