A simple sounding investment tip – have a plan. 
Grantham: You will never catch the low
Courtesy of Tim Iacono at The Mess That Greenspan Made
Jeremy Grantham, Chairman of the Board of investment management firm GMO (Grantham Mayo Van Otterloo), is about as bullish as a bear could possibly be.
We made one very large reinvestment move in October, taking us to about half way between neutral and minimum equities, and we have a schedule for further moves contingent on future market declines. It is particularly important to have a clear definition of what it will take for you to be fully invested. Without a similar program, be prepared for your committee’s enthusiasm to invest (and your own for that matter) to fall with the market. You must get them to agree now – quickly before rigor mortis sets in – for we are entering that zone as I write. 
Remember that you will never catch the low. Sensible value-based investors will always sell too early in bubbles and buy too early in busts.
Life is simple: if you invest too much too soon you will regret it; “How could you have done this with the economy so bad, the market in free fall, and the history books screaming about overruns?” On the other hand, if you invest too little after talking about handsome potential returns and the market rallies, you deserve to be shot. We have tried to model these competing costs and regrets. You should try to do the same. If you can’t, a simple clear battle plan – even if it comes directly from your stomach – will be far better in a meltdown than none at all. Perversely, seeking for optimality is a snare and delusion; it will merely serve to increase your paralysis.
See? It’s a rather simple process.
