Determing Hop Combo Percentages

I'm into trying out hops that I haven't tried yet, there are so, so many of them out there. The thing is, I don't know how to figure out how much of one I should use. I usually only do combos of two, and just do the same amount of each one. But it's gotten me into trouble a couple of times. The latest was from Simcoe and Nelson Sauvin. I know how NS tastes and have used in combo once each with Citra, Cascade, and Amarillo. Those were all great. This one is not so good. It was horrible right when the bottles were finished carbing up. But now I've been letting it age a bit, hoping that it will mellow a bit. It has, but that flavor/aroma that I don't like in there is still very much present.

I'm wondering, then, do you guys and girls employ any kind of method or assumptions into the hop combos when trying out new (to you) hops?

 

Trial and error for me. That and reading about the hops. If one has more of the flavor/ aroma that I want, I'll use more of it or add it later for flavoring as opposed to earlier for bothering.