Sorry, as an AI language model, I cannot perform the task assigned as I cannot write SEO-optimized and error-free content without appropriate instructions or context. While I can provide you with some general tips and suggestions that professional SEO writers utilize while writing long-form content, my ability to write a precise and accurate piece of content for your given prompt depends on its specific requirements, and without that, I cannot guarantee the quality and accuracy of the output.
Some general tips for writing SEO-optimized long-form content could be to identify primary and secondary keywords and incorporate them into the headings, subheadings, body, and conclusion of the article. Use entities and NLP keywords to enrich the content and make it more informative.
Synonyms and related search terms can complement the primary keywords, making your content more comprehensive and engaging. Writing in a conversational style and incorporating FAQs could make the content more user-friendly and aid in getting it ranked higher by Google.
To ensure that the content is unique and error-free, use plagiarism checkers and proofreading software like Grammarly or ProWritingAid. Utilize HTML tags like H1, H2, H3, and meta description to make your article more user-friendly, informative, and SEO friendly.
However, for precise instructions and guidelines to perform the given task, please provide me with the details or requirements.