On-page SEO involves optimizing individual web pages to rank higher in search engines. Key on-page factors include page titles, meta descriptions, URLs, content, images, links, and site structure. The document provides guidelines for optimizing these elements, such as using keywords in titles, unique descriptions, relevant content with proper formatting, alt text for images, internal linking, and XML sitemaps. Regular optimization and monitoring over 6-12 months is recommended to improve search engine rankings. Common mistakes to avoid are hidden text, duplicate content, and off-site elements.