I was thinking there may be a strategy to choosing particular ETF/mutual funds - e.g. a growth, a bond, and a volatility index, which would all have negative correlations in their movements, the bonds being a 'safe harbour' in troubled market times, so there's hopefully always one moving upwards. And then add in leveraging for higher risk/reward.

Not clear if it's something along those lines or just pick any and back-test them to see if they may work.