We may not be starting a secular bull market that "lifts all boats" for another 5 to 7 years, maybe longer. The process of bringing down valuations to real bargain, and that is what the "job" of a secular bear market is, is lengthy, interrupted with minor cyclical bull moves, yet the main trend stays down for a long period of time. If you are playing the market in order to retire, or capture back what was lost in the last two years, I am afraid that I have no good news. At best, if you feel you have the "rythm" of the market" in your veins, you may want to buy for three weeks to few months those major uptrends offered once or twice a year in either a group of stocks you know will participate in such short term bull moves, or in mutual funds, and stay out when the market become cocky again. Frankly, timing is tough and I don't know anyone that gets it right all the time (turnips included), but when you get major fear in the market (as we are slowly getting here), is usually a good time to plunge, and then when exuberance gets amok, time to get out. If you don't step out of the way of those declines, you are assured financial destruction. In any event, you should not commit everything to equity here (depending of course on your retirement resources and your expected needs at retirement) or at any time from here to retirement.
Zeev