You're welcome, Judas. Orchestration is definitely a daunting subject. As much orchestra music as I try to write, I certainly can't claim to have a true grasp of its rules and theory. Mostly I just listen to a lot of orchestral music and, like you, just write what sounds good to me. In any case, if you're interested in studying it, the Garritan website has a great free online course here .
All the Best,
Jake