This article is not intended as a complete guide to SEO, only to highlight how certain features of GetSimple can be used for SEO purposes. It refers directly to statements made in Google Webmaster Academy.
The GetSimple Default themes provide individual pages with html titles in the format Site Name - Page Heading which google says is at least adequate. If you don't want to be tied to that format you can change it by editing the template or install the Custom Title plugin which will allow you to write whatever you wish in the title of each page.
In the CKEditor click on each image and easily check and edit the alt text.
Easily done in Page Options
GetSimple automatically creates an xml sitemap in the right format in the root of your site. You can manually submit the sitemap to google or use robots.txt
An html sitemap can be made by several plugins or in the same way as any page.
A GetSimple 404 page will by default include the site navigation links, but you can customise it further - Custom 404 Page
And the other social links as well are added by plugin or manually.