If you want to *ENSURE* your FULL title tag shows in the desktop UK version of Google SERPs, stick to a shorter title of between 55-65 characters but that does not mean your title tag MUST end at 55 characters and remember your mobile visitors see a longer title (in the UK, in January 2018). What you see displayed in SERPs depends on the characters you use. In 2019 – I just expect what Google displays to change – so I don’t obsess about what Google is doing in terms of display. See the tests later on in this article.
I think ranking in organic listings is a lot about trusted links making trusted pages rank, making trusted links making trusted pages rank ad nauseam for various keywords. Some pages can pass trust to another site; some pages cannot. Some links can. Some cannot. Some links are trusted enough to pass ranking signals to another page. Some are not. YOU NEED LINKS FROM TRUSTED PAGES IF YOU WANT TO RANK AND AVOID PENALTIES & FILTERS.
Another excellent guide is Google’s “Search Engine Optimization Starter Guide.” This is a free PDF download that covers basic tips that Google provides to its own employees on how to get listed. You’ll find it here. Also well worth checking out is Moz’s “Beginner’s Guide To SEO,” which you’ll find here, and the SEO Success Pyramid from Small Business Search Marketing.