Google suggests to use tree-like navigation structure. The most important pages should be one click from your home page. These pages should be optimized for more general (and more competitive) keywords. If you will comply with this suggestion your pages with more competitive keywords will get higher portion of pagerank. Pages containing less competitive keywords should be in tier 2 (2 clicks from homepage). These pages need not so big portion of pagerank to be ranked well in SERPs. It is possible that you will need more tiers if you run larger website. You should consider to provide users with links between lower-level pages. It helps to make your site navigation more clear and if you use keywords in the anchor text, you get some very important "points" from search engines.
Time from time check your site for broken links. There are some quality free programs or online services which will do it for you automatically. From the point of search engines, the broken links are sign that something is not ok. A lot of broken links can hurt your search engine positions.
Avoid pages with extremely long content. Google suggests keep the page size under 100 Kb. In fact, Google evidently prefers smaller pages. It seem be logical because sites with basic information and links to detailed info are more clear then one single page where the webmaster placed all available information.
Site updates
Search engines like fresh content. Keep your site up to date -- both, the visitors and search engines will like you.
Quality content
There are some ways how search engines determine if your content is useful for the visitors or not. If the visitor come to your website from Google and immediately click the back button, he probably didn't find what he was looking for. The average time spent on your website is very important factor to determine website quality.
Another factor used by search engines to determine website quality is the number of particular pages. If your website consists of many hundreds pages, you more likely offer higher value to your visitors then a website which consists of a single page.
Age of the site
Google does everything to protect quality of its search results. Spammers usually register domains for one year, try to quickly achieve good positions and because they get banned in a few months, they don't renew the domain name. Instead they register a new one and start the spamming procedure again. From this reason the older sites are more preferred by Google. If you have five years old web which is regularly updated you will have big advantage against new websites.
When you register a new domain name you should register it for more then one year. From my own experience when I registered 2 domain names for one year I didn't achieve top positions in the first year. A few days after domain renewal there was a big boost in SERPs. When I registered new domain for 10 years the site was out of sandbox after 3 months.
So this was the Guide Through On Page SEO Factors. I hope that these information will help you to rank better in search engines and get more visitors to your website. Good luck!
