Highlighting Keywords..!
Keywords in bold/italic/emphasized/h1 definitely help in improving rankings. Since making them bold is nothing but highlighting. And so the highlighted text will be watched by the Crawlers.
Note: Do NOT use them everywhere the keyword appears. An emphasized keyword for that page can be repeated for about 1-6% of the total words in that page.
Make the keyword bold if it comes at the "start" of a paragraph or in the "middle" of the paragraph