This is the process I usually follow when I write a guest post for my clients' link building campaigns .
I do not claim that it is the best method nor that it is the perfect one, however it has always brought excellent results.
The first thing to do is to identify a topic that is themed with the host site and that at the same time offers a "handle" to insert a sentence in which to insert the anchor text with which you will link your site.
The topic of the guest post must absolutely NOT be the same as the one covered by the page you are going to link .
The Anchor text that will link your site must be seen by the reader as an invitation to deepen an aspect / topic that has been treated marginally in the article.
Using one of the many SEO tools (semrush, ahrefs, etc.), it is advisable to carry out a keywords research on the identified topic and identify long tail keywords composed of at least 4 terms , preferably 5, with search volume between 90 and 360 monthly searches .
Search Google for the identified keywords and note the number of results that appear in Serp.
The goal is to find a keyword for which the Google Serp provides less than 10,000 results (even better if you find one with less than 5000 results).
Write the article optimizing it for the low competition long tail keyword identified with the passage above.
Write naturally and not forcedly so that the content is really useful for the user.
The article must contain a sentence / sentence that is consistent with the rest of the text and that, at the same time, is preparatory to the insertion of the anchor text with which you will link our site.
If you have done everything in the best way, you will find yourself a guest post well positioned on Google , which receives traffic (therefore read by users) and which could also bring you referral traffic deriving from clicks on your link.
It goes without saying that a backlink from an article of this type is much more advantageous and "performing" than a backlink placed in an article written "just for", without having been optimized for any keyword, with content of no interest, specially created and exclusively to put the link in it (badly).