Some blog platforms, like TypePad, already convert all bolded words and phrases in the site's "Rich Text" editor with the strong tag (written as <strong> with closing tag </strong> ) but, if you're not sure, you may want to check.
Simply select the HTML editing option in your blog platform's compose window or right click and select the "view source" option.
The XHTML strong tag is quite different from the bold tag (coded as <b> with closing </b>) because it does more than simply change the appearance of text.
Using the strong tag adds emphasis to keywords and phrases which are detected by search engines like Google.
Though it's not advisable to overuse the strong tag in any blog post or Webpage, one way to add extra keywords to your article is to add the tags to bullet points or subtitles.
For more on choosing keywords, particularly for ecommerce blogs and Website's, see this segment from Ford Saeks at ProfitRichResults.com: