Canonical Tag Best Practices
In order to use canonical links effectively, it is worth following a few best practices that will help you avoid mistakes and improve your site's positioning. Here are a few of them.

First of all , it is worth making sure that canonical tags are used only where necessary. There is no point in adding them to every subpage, it is better to focus on those places where there is a real risk of duplicate content.
Secondly , it is important that canonical links are HTTPS-compatible if our site uses this protocol. Otherwise, search engines may treat the HTTP and HTTPS versions as two different pages.
Third , it is worth remembering that canonical tags can be used not only within our own site, but also for content published on other sites (e.g. guest posts). This will help us avoid problems related to duplicate content and "dilution" of SEO value.