It's simple. Take a blog that's been around for a while. It can be optimized for the search engines or not. Doesn't matter.
Next - install Measure MY SEO plugin on your wordpress blog. Go into each post/page and put in the keyword(s) that each post should be optimized for.
Check your scores. If you don't have 100% for each blog post, there is room for improvement! And we guarantee that you will NOT have 100% for each blog post, as it's easy to miss something before you used Measure My SEO.
Finally, just follow each suggestion Measure MY SEO gives you... it can't get any easier than this!