Don’t be obsessed with keywords. Write titles and tags as a user would search on Google. For this you can use Google trends and Google keyword tools. Try keeping them in the order of words that visitors might type, although search engines do take into consideration variations in the order of keywords.
The H1 tags you create in your post (which means your headings and sub headings) to indicate to users the important or key content in that section, must be written naturally. The keywords here must reflect the core of the content in that section. You should never try to use keywords that are meant to cheat search engines into believing that the content is different. Write titles and tags that reflect the content following them. Be ETHICAL.
Example: If you are doing a post on the new drug testing for skin cancer, then the correct H1 tag is: New drug for Skin Cancer being tested and not: Treatment for Skin Cancer Found
You shouldn’t use the second tag just because you know people are searching for “treatment for skin cancer.” Search engines’ algorithms are very intelligent and will easily find out that the content is different from the title given. And will not give you benefits. Rather, you could be penalized if it finds that you do this once too often.
Tip: Write titles and tags naturally as users would use them. Don’t overdo or use non relevant keywords to optimize. Search engines are smarter than you think they are.
Remember that the job of search engines like Google is to serve useful and relevant content to searchers. So they’ll find your content anyway if it’s good enough. Focus on writing good content, use ethical SEO techniques and the traffic will come.
Try not to stuff keywords into the title, tags or body. This will result in a negative experience for users and Google will penalize your ranking for those pages or keywords.
Always attempt to give rich information to visitors.
Use keywords that are relevant.
Place them in the order that user would use while searching for your information.
And you are on your way to a better page rank, user satisfaction and loads of traffic.