A recent Google update (Panda and Penguin) has included a new algorithm to identify websites which are over-optimized and is penalizing them. Below are some important points you can follow to avoid over optimization penalty:
1. Do not throw way too many keywords on a single page.
2. Stop exchanging way too many links.
3. Stop stuffing too many keywords in a single page.
4. Stop doing too many keyword rich internal linking without any quality content.
5. Do not stuff keywords in title and body tags.
6. Make body content more valuable.
7. Do not build 1000s of links in short span of time.
8. Vary your anchor text for link building, don’t use same anchor text everywhere.
9. Spend 50% of your time to social media and share interesting stuff to Twitter, facebook, stumbleupon, digg, Google plus.
10. Make your image alt texts as details as possible.
11. DO-NOT use/follow Black-hat SEO techniques.
If you have any query to troubleshoot Google Panda or Penguin penalty contact me at firstname.lastname@example.org or +1 646-736-1319