Only enter SEO – What is your advice?

Doing everything possible to follow and understand the Google webmaster guidelines is a must.

But the only thing you should not do is keep changing the URL of your website over the years (if you really want stable SEO traffic to arrive on your site for many years, you should not keep changing the URLs). No matter what you do, avoid using a CMS that automatically generates many URLs for the same page. WordPress as CMS is probably better than most other CMS, since it is easy to take control of the URLs of your site. And, of course, if you prefer to create your website without any CMS, then you must follow the "never change URLs" rule.