To optimize your website's images for search engine indexing and inclusion in image search results, consider the following best practices:

1. Image Relevance: Ensure that your images are relevant to the content of your website. Use descriptive filenames and alt text that accurately describe the image content.
2. Image Size and Quality: Optimize your images for web use by reducing file size without compromising quality. Large image files can slow down your website's loading speed, which can negatively impact user experience and search engine rankings. Use image compression techniques to reduce file size while maintaining visual quality.
3. Image Format: Use widely supported image formats such as JPEG, PNG, and GIF. JPEG is commonly used for photographs and complex images, while PNG is suitable for images with transparency or simple graphics. GIF is typically used for animated images.
4. Image Dimensions: Use appropriate dimensions for your images based on where they will be displayed on your website. Avoid using excessively large images that need to be scaled down by the browser, as this can impact loading times.
5. Image Sitemaps: Create an image sitemap and submit it to search engines such as Google. An image sitemap provides search engines with additional information about your images, including metadata such as image titles and captions, which can improve indexing and inclusion in image search results.
6. Schema Markup: Use schema markup to provide search engines with structured data about your images. This can include information such as image subject, author, and license type, which can improve the visibility of your images in search results.
7. Mobile Optimization: Ensure that your images are optimized for mobile devices, as mobile users represent a significant portion of internet traffic. Use responsive images and design techniques to ensure that your images are displayed correctly on various screen sizes.

By following these best practices, you can optimize your website's images for search engine indexing and inclusion in image search results, improving the visibility of your content to users searching for relevant images.