Don't really have any. For the most part, they trade together anyway. I think your best bet is just to go with GDX. A little less volatile and you also avoid individual stock risk.

Specifically, what I do with GDX is to sell a naked put (front month) when it drops and begins to turn up. I get 2-3% per month on the option, and if it gets assigned, I sell a covered call - for more income. It doesn't blow the doors off, but it's a nice easy way to get income in a choppy market.