What are the things you have done for your sites? Did you check if you got hit with Penguin or Panda?

I think you should start in analyzing your site structure, back link profile and keyword ranking before you do other stuffs.

Make sure that you come up with good promotion plan in driving targeted traffic to your site. If you are optimizing that site for quite a long time, you might want to check your Google analytics and webmaster tools and see what are the terms are mostly used by users to visit your site and try to leverage from them.

Increase Social Media Presence, your site will get traffic...

Try to increase your blog backlinks (High PR). This will definitely increase your organic traffic.

do proper seo........ onpage and offpage.............