AG4Life - 2:24 am on Oct 20, 2011 (gmt 0)
From my own personal experience, removing technical issues proved to be the biggest change (went through WMT's HTML Suggestions), and probably contributed to the partial recovery the most. Other than that, page speed improvements are also important, and as my website is content based, I've also added more fresh, relevant, high quality content (not necessarily more content in total, just more of the type of content that, regardless of Panda and whatnot, would attract visitors to stay longer and to come back).
It's also good to get more non Google traffic, which is a necessity these days anyway to counter whatever concoction Google cooks up next. I have a feeling Panda seems to have a less full on effect on websites that does not rely on Google traffic as much, which kind of makes sense when you think about it, as content farms and scraper sites would all have most of their traffic coming from Google, whereas a high quality website would have traffic from everywhere.