A former co-worker of mine used the "buy at a price, sell half when it doubles" to great success. And by having a trailing stop, you can make sure what you keep will always sell for at least the 2x value. The only real risk, of course, is that if you buy and it immediately starts going down, but he would use a "stop loss" (I forget the term), which would make it automatically sell for a minimal loss if it immediately starts going down. Of course, the immediate downslide could just be the pre-cursor to a long and significant rise, so you miss out on that if it happens, but that seemed pretty rare, especially for IPOs.