Well, in 2008 many of my shares took a big hit to their prices, probably around 40-50%, but their dividends, which is what I most focus on, barely changed, and those that did reduce them, pretty much recovered over the next couple of years.
So what did I do, well nothing with the shares I had, I just left them to recover in the years that followed. But after the crash, I invested a lot of money in the next 2 years (well I multiplied my share holdings by 20), and they've done very, very well.
So my approach was, ignore the dips, and then try to buy as much as possible after the dip.