what i do is decide on my topic...then i find a keyword based on that topic. Once I find a good keyword, I will use that in my title, first paragraph, then the rest of the content will flow naturally based on the keyword

What I have been doing is deciding upon my content first and then trying to find various combinations of keywords that could be titles and used once in the first paragraph. Then I check them out on the keyword tools to see which one ranks the best. Finding good keywords can help you determine what to write about too. I'm still new at this, but hopefully that is a good answer to your question.