Verify metatags for every page: 'title', 'keywords' and 'description'.
Verify language tags: metatags and header tags 'lang'.
Verify equivalence of domains with 'www' or without, and make redirections.
Verify subdomains or subdirectories in all languages.
Verify headline tags H1 , H2, H3 on every page.
Verify compatibility with Explorer, Firefox, Chrome and Safari.
Create Schema.org metatags.
Create canonical 'tags' on all pages.
Create 'nofollow' required links.
Create robots.txt and sitemap.xml files with automatic updating.
Create OpenGraph metatags for Facebook, Twitter and other social networks.
Create personalized page for 404 errors.
Create 'alternate' tags of links to languages.
Active Google Analytics.
Activate the cache memory and 'etags'.