On page SEO can be summarized in one word; content.
On page SEO is what is displayed on your website, what users and search engines see, and what you hope will get you boosted up the search engine rankings. The most prominent feature of on page SEO is copy.
If you know anything about SEO you’ll know the key to a successful SEO campaign is in fact good keyword research. Target keywords with no search traffic and no one will see your site – even if it is number 1 in Google. Target keywords that have too many searches and are too competitive, and you’ll find it hard to make any ground when it comes to a coveted first page ranking. It’s important to find the balance between too much competition and too little competition.
The key to on page SEO is quality content – and lots of it. In times gone by website owners could get away with spun content, or copy they’d had written by someone with a less than adequate command of the English language. Since the Google Panda update the emphasis on quality content has never been stronger – Google are all about keeping users happy – so if you’re pumping out pages of crap that no one wants to read, they’ll suppress your site far down the results – even if the articles are keyword rich.
Aside from great copy there are other things you can do, like making use of H1, H2 and H3 tags (including your main keyword in each), including your keyword in the page URL (and domain name where possible), and maintaining some sort of internal linking structure.
For those who are using WordPress as their chosen platform for building a website there are a few worthwhile SEO checklist plugins out there that will help you in your quest to optimize your website. They’re not cheap – but they are concise and straight to the point. Remembering every single component of effective on page SEO is hard, so it’s nice to have a visual checklist on each page you can use to assess your site.