How do you optimize your content for search engines?

As Writer Point of View your content should be easy to understand readable and properly formatted , Search Engine use many indicators (Few Mention Below) to rank your content readability , They also respect you so when you use any Keyword in Heading Search Engine understand you want to highlight that Keyword , Same for Emphasis , Italc each has its own Score 

Always try Use Small Paragraphs and easy words instead of long and uncommon words that increase your readability score thats all i think

If you are talking about Overall SEO point of view they are is lot of factors which involve including the way page code.

Flesch Kincaid Reading Ease

Flesch Kincaid Grade Level

Gunning Fog Score

Coleman Liau Index

For Testing: http://read-able.com/

I allow it :) 

Must be unique and attractive but most importantly in compliance with Google rules. Best way to use All google SEO tools , for example use keywords from google keyword tool, submit to webmaster tool and then track through analytics. 

Register with Google local businesses

Create unique accurate page titles

Improve the structure of your URLs

Use words in URLs

Make your site easier to navigate 

Dedicate some time to writing really great content. The saying goes that you should write for people first and search engines second. This basically means you should be creating really quality pieces that are useful and engaging for humans because the search engines will recognise your efforts. Your readers will share your work generating additional backlinks, not to mention extra traffic, and search engines will recognise your quality piece because it will flow naturally with not too many keywords (something which is penalized in the post Penguin Update world).

As Writer Point of View your content should be easy to understand readable and properly formatted , Search Engine use many indicators (Few Mention Below) to rank your content readability , They also respect you so when you use any Keyword in Heading Search Engine understand you want to highlight that Keyword

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Optimization of content relates to applying SEO (Search Engine Optimization) techniques to your texts (and images too) and any other elements that define your content and can be optimized. SEO in such case, is mostly two-side:

On-site optimization: relating to your content on your website, blog or "social profile". You should make sure your content carries your desired keywords; the ones that would lead visitors to your website after they type in a certain "search string" or "search term" into Google or any other search engine. You can use available on-site tools to enhance SEO for you content, through adding tags, description, and textual-links without too much jamming, stuffing or cluttering. Avoid misuse (duplicate content, keyword stuffing and other so-called black-hat SEO tactics)

Off-site optimization: relating to promoting the web locating of you content to the world wide web, through increasing external links to your content (or part of your content). The number of external links added to the authority (importance or high PageRank) of the voting sites will make your website rank high in search results. This is done automatically by search engines themselves, which scan your site (index it) using certain algorithms to determine relevance of your content to their users. Avoid misuse: generally avoid paid linkbuilding unless you get guarantees it is legitimate, don't build links through spammy actions. BE PATIENT, good and lasting SEO takes time!