Content optimization... very broad term!
When it comes to creating quality content a good rule of thumb is to write for the user first, the search engines second.
I will give a good example of quality content optimization:
Imagine you have a site... with 1000 blog posts and they all go one after another in date order. They all cover a wide range of subjects and to find the content you want would be very tricky.
Content optimization is important because you breakdown these into categories.
Blog Home -->
Cars --> (Blog Posts relating to cars)
Bikes --> (Blog Posts relating to bikes)
Bike Parts --> (Blog posts relating to bike parts)
For the URL, the blog would form something like:
This would breakdown to the user, and also to search engines how the content is structured, thus providing good optimization.
When it comes to the actual article writing, make sure your targetted keywords are mentioned enough but not too much. Feel free to "bold" the text which are your keywords as this helps too. A good keyword density is between 1.5% to 4.5% for best results, but it is trial an error.
Hope this helps.