Determine the parent themes for your topic.

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create a blog

etc

Then gather stem all the related terms. The purpose is to do research on the stems to se if they are possibly more profitable than the one you originally identified.

Then gather keywords for all variations under the theme. Under blog hosting here is a very short list of possibilities:

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blog free hosting wordpress
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The goal is to show the search engines that your website is 100% on target for each of the parent themes of your site which in turn are 100% on target for the main theme of your site. The only way to do this is to strengthen your themes by adding content.

Each article, product page, product description, content, etc., must fall within (under) their appropriate parent theme. If the content within your parent themes does not match your parent theme then you will have problems ranking due to relevance issues.