If you are among those whose website was penalized by Google and are still recovering then hopefully this should help. Google panda dislikes duplicate and irrelevant content for
SEO reasons so if your website was penalized , it means it definitely did something to cheese Google off. Hence the ideal way to combat this issue is to:
1) Complete change of content in website
2) A wiser approach would be to identify the pages that have bad content and develop them effectively
You need your content to be unique, relevant, optimized and very informative so as to attract visitors and allow Google to index your page.