The subject and verb must match in number. Use "She writes" (singular) but "They write" (plural).
Most sentences follow a Subject + Verb + Object order (e.g., "She [S] reads [V] books [O]"). English Grammar: Step by Step
Practice with short paragraphs or diaries. Tools like the Grammarly Editor or Hemingway App can provide instant feedback. The subject and verb must match in number