Jon, if you're crossing something new, it's going to be 99% trial and error--and be prepared to wait 5 years to find out the first of your results. Even if you're remaking something that's already been done, just using different cultivars of the same grex can lead to unexpected outcomes, despite however much research you put in.

Look to see how the grexes you're trying to breed performed in other crosses: that will at least give you some idea--not definitive, by any means--of what dominant traits a certain parent usually passes down. In Cattleya breeding, for instance, B. nodosa almost always passes its flower's shape, regardless of which plant carried the capsule. So when you make your cross, have each parent carry a pod from the pollen of the other and see if there was any difference.

I wish things were more cut and dried, but unfortunately, they're just not. Be that as it may, some of the most sought-after hybrids were created when someone said, "I wonder what happens if..." and they just went ahead and worked the old toothpick.