Most effective way is to make it look natural and avoid forcing keywords. Hopefully I am wrong but I have a feeling that you are looking for a simple shortcut like the ones that used to exist years ago but no longer work in Google.
Here are some ways I approach content and keywords:
-Each page should only be about one idea/concept.
-Don't focus on keyword density, think about supporting synonyms
-Don't settle for just unique content, you want valuable content
-Siloing can be a good concept but in the extreme is bad
-It can help to lighten up the header & sidebar in Wordpress