How do you catch the bottom? You can't. No one knows how low the market will go. The FTSE 100 could go to 4,000, or 3,000, or lower. Markets tend to overshoot. But the further shares fall, the better your long-term returns. Fighting the psychology is the trick. If you invested £1,000 in the London market in late 1973, halfway through the crash, after one year your investment would have been worth just £500. But if you held on, today it would be £65,000.