QUOTE: “They follow the forms you gather data you do so and so and so forth but they don’t get any laws they don’t haven’t found out anything they haven’t got anywhere yet maybe someday they will but it’s not very well developed but what happens is an even more mundane level we get experts on everything that sound like this sort of scientific expert they they’re not scientist is a typewriter and they make up something.”  Richard Feynman, Physicist 1981
You can probably include up to 12 words that will be counted as part of a page title, and consider using your important keywords in the first 8 words. The rest of your page title historically counted as normal text on the page, but recent tests (2019) would indicate this is no longer the case. Words beyond the 12th word may be completely ignored by Google.
QUOTE: “Many websites are eager to tell users how great they are. Some webmasters have read these rating guidelines and write “reviews” on various review websites. But for Page Quality rating, you must also look for outside, independent reputation information about the website. When the website says one thing about itself, but reputable external sources disagree with what the website says, trust the external sources. ” Google Search Quality Evaluator Guidelines 2019

Structured data21 is code that you can add to your sites' pages to describe your content to search engines, so they can better understand what's on your pages. Search engines can use this understanding to display your content in useful (and eye-catching!) ways in search results. That, in turn, can help you attract just the right kind of customers for your business.
If you have a commenting system (like Drupal, Joomla or WordPress) that allows for search engine friendly links (commonly called dofollow links) from your blog or site, you will probably, eventually be the target of lots of spam, be complicated in tiered link schemes and potentially fall foul of Google’s webmaster guidelines on using the attribute in certain situations.
The SEO starter guide describes much of what your SEO will do for you. Although you don't need to know this guide well yourself if you're hiring a professional to do the work for you, it is useful to be familiar with these techniques, so that you can be aware if an SEO wants to use a technique that is not recommended or, worse, strongly discouraged.