One of the things you should do is to determine where your backlinks are coming from. “Backlinks – Who Is Linking to Me” will show you how to find out who is linking to your site so you can make sure you don’t have any bad backlinks. You can use Google’s Webmaster Tools to get rid of bad backlinks.
As long as you are creating great content that people are interested in, then you don’t have anything to worry about. The Penguin Update is designed to penalize sites that use black hat SEO and link spamming.