The keywords are those with which you want the user to find your content when searching on Google. For this, you have to choose the ones that best suit the subject you are writing about, look for others related to this same topic that may be of interest and use them head-first in your content.
It is also 100% recommended that you use them in the sections that I have explained before (URLs, titles, descriptions, headlines … ) so that Google finds it better. In this way, when someone searches on that topic and uses one of those keywords, Google will take into account whether your website has them or not.
For example, if you write an article to recommend the best hosting for WordPress, a good tip may be to use the keywords “best” and “hosting”.
And it is logical to think that people look for “the best hosting for WordPress“, “which is the best hosting“, “hosting for WordPress“, etc.
My advice is that you do not obsess over keywords. There are analysers, tools, density meters, word counters … The truth is that I think it is much simpler than all that.
It is clear that you have to use keywords and related concepts for Google to know what your content is about , but is not it logical that you end up using all these keywords when you write about a specific topic?
The best thing you can do is write your content naturally, without thinking about keywords.
Check it when you have finished it, and then yes, you can analyse what they are. When you have them, you can substitute a word or phrase with your keywords or even with those used by your competition; But be careful, make sure that the phrase or paragraph does not lose the meaning you wanted to give it.