There are several best practices for implementing SEO (Search Engine Optimization) techniques using PHP:

1. Friendly URLs: Use PHP to generate clean and user-friendly URLs that include relevant keywords. Modify the .htaccess file to rewrite the URLs and remove any unnecessary characters or parameters.

2. Meta tags: Use PHP to dynamically generate meta tags (title, description, keywords) based on the content of each page. Make sure to include relevant keywords and concise descriptions that accurately reflect the page’s content.

3. Canonical URLs: Implement canonical URLs using PHP to avoid duplicate content issues. Make sure to set the canonical URL based on the preferred version of the page and redirect any alternate versions to the canonical URL.

4. XML sitemaps: Use PHP to generate XML sitemaps dynamically, including all relevant pages of the website. Ensure that the sitemap is updated regularly and submitted to search engines.

5. Robots.txt: Generate a robots.txt file dynamically using PHP to control the crawling and indexing of web pages by search engine bots. Make sure to include any necessary rules to disallow irrelevant or sensitive pages.

6. Page speed optimization: Use PHP to implement various techniques for optimizing page speed, such as caching, minifying CSS and JavaScript files, compressing images, and reducing server response time. Faster-loading pages have better chances of ranking higher in search engine results.

7. Schema markup: Use PHP to add schema markup to pages, providing search engines with additional information about the content on the page. This can help improve search engine visibility and enable rich snippets in search results.

8. Mobile optimization: Use PHP to dynamically detect and serve responsive or mobile-friendly versions of your website to improve user experience and search engine rankings.

9. SEO-friendly redirects: Use PHP to implement 301 redirects for pages that have been moved or renamed. This ensures that search engines understand the new location of the page and pass any existing SEO value to the new URL.

10. URL canonicalization: Use PHP to enforce URL canonicalization by redirecting all non-canonical URLs to the preferred URL version (e.g., www vs. non-www, HTTP vs. HTTPS). This helps consolidate SEO value and avoids duplicate content issues.

Remember, while PHP can be a powerful tool for implementing SEO techniques, it’s important to consider other factors like quality content, backlinks, and user experience when optimizing your website for search engines.