If you need a checklist to provide it to a developer so he can check and work on this list, you will find my list for developers below.
Create and install your Google Analytics tracking code on the website.
Create a sitemap.xml page for all website links.
It's very important these days to have SSL for the website. The easiest way to install it is to use Cloudflare.
Favicon is the browser icon that is showing before your website address on the browser. The developer can help to set your favicon.