The links that follow represent the bare minimum that you must consider to give your website a fighting chance. Decide if you are using www or no www and stick with it forcing compliance in the .htaccess file.

• Host on a fast server, this will only cost a few dollars per month more than a slow one.
• Create a .htaccess file with 301 redirects and force https protocol
• Setup Google Search Console
• Setup Google Analytics
• Create an XML Sitemap
• Test your website - mobile-friendliness
• Test your website for speed
• Test the Structured Data on your webpages
• If your pages are Accelerated Mobile Pages run the AMP validator
• If you are using Google maps get an API key from Google
• If using a data entry form use Google's I am not a robot 
• Working with Google's AMP cache.