Here are a couple of resources that can help you determine if traffic changes to your site (whether up or down) are the result of Penguin 2.0 or good (or bad) SEO to your site:
Thoughts on SEO, social media, and other geeky things.
Just who do I think I am? http://zimorama.com/
When I retire I want to work on a PhD in history and teach Western Civilization as a TA. Meanwhile I am starting a list of philosophers every SEO should know. That list starts with:
Checklist: Another easy website optimisation is to make sure page titles are unique across your entire website. Titles are critical to giving users a quick insight into the content of a result and why it’s relevant to their query. It’s often the primary piece of information used to decide which result to click on, so it’s important to use high-quality unique titles on your web pages.