Squarespace

Squarespace has a large selection of videos and guides to help you, if you're just getting started:

SEO

The following formation was pulled directly from squarespace.com.

Sitemap
Site speed
SSL certificate
Image & alt tags
Meta tags -- titles & descriptions
Verify your site with Google Search Console - After you've verified your site with Google, you can manage your site’s presence in Google search results and see how visitors find you.
Request that Google index your site - This asks Google's bots to review your site and update search results with your new content.
Verify your site with Bing Webmaster Tools - Verify your site with Bing to manage your site’s presence in Bing and Yahoo search results.
Connect to Google Analytics - Track visits and other reporting on your site through our built-in integration with Google.
Redirect changed or broken links - If you change the URL slug on a page on your site, create URL redirects to forward visitors who go to the old URL to the correct page.

Add alt text to images - In addition to increasing accessibility for visitors who use assistive screen readers, alt text also helps search engines identify the content of a page.
Add social sharing images and SEO descriptions - As you add new pages to your site, give them social sharing logos and SEO descriptions.
Give your images readable file names - Image file names may also be used as alt text. Follow our best practices when creating your image file names.
Add tags and categories - Organize your blog posts, products, gallery images, and other content with tags and categories to help visitors navigate your site.
Link to your site's content - Where it's relevant, use content links to connect the pages on your site to each other.
Customize URL slugs - As you add pages and collection items, ensure their URLs reflect the content of the page.
Keep your pages nimble - To ensure your site loads well, we recommend keeping images under 500 KB and overall page size under 5 MB.