Bung,
I have been working this into my strategy with some success, so I will just share a few ideas.
With ETFs, it makes sense to pair these with another ETF since the moves are about the same. I have hedged some shorts against some etfs, but the problem is that on an up day, my shorts go up more than the dollar value of the index.
It would seem on the surface and this is the next leg of my research this weekend to find stock to stock pairs in different industries. For instance I noticed that truckers hit a new high. So I plan to go long the a strong co and short a weak one.
It has also helped to set them up at the same time. Perhaps even writing out your entry, exit and stop loss goals. For instance on Friday I anticipated a sell-off much sooner than it came. As a result I sold part of a long at the open for a gain, which was painful until about 3.
The other thing is to take a profit when you can. When the pair becomes profitable it makes sense in some cases to take it off. Since correlation is not perfect, a negative divergence can blow up the pair.
Regards