Fortunately, or unfortunately, the process is a combination of personal experience gained through a lot of trial and error, and asking for opinions on your efforts, and studying other peoples' work and asking them how they achieved their results. Many have totally different ways of acheiving similar goals. In some ways, real life mixing jobs (with real live recorded instruments) demonstrate parallels, but in many ways, the VSL process is very different. I am still unsatisfied with many of my results, but am coming to terms with the following revelation:
The better my arrangement before I touch any reverb settings, the better it will sound in reverb. If your original dry VSL arrangement sounds like a fairground organ, adding reverb will only exacerbate the situation. Reverb is not to the VSL man what grouting is to a tiler! Reverb will not fix poor quality VSL orchestration. I don't care how good the reverb quality is - mud is mud. If this idea disturbs you, think of rehearsing the Vienna Phil in a school hall. The sound will be dry and a little boxy, but still rather good. Then transfer them to a nice sounding space for the concert and PRESTO!
Thus, a lot of people here are not actually suffering from post-production and mix problems, but from not having spent enough attention to detail at a pre-production level, or even (in the nicest possible way) lack some experience in basic music harmony, theory and orchestration. Combining technology with music is asking a fair amount from one brain. Many musicians I know are purists and don't even have a computer. Others have embraced technology in their own way, and are making it work for them.
Study scores, ask questions, listen to classical recordings of orchestras, and then take a step back and see if your stuff is close. This is of course assuming you are happy with the level of your knowledge of VSL from a technial point of view. But don't ever lose sight of the fact that, in spite of the frustrations you might encounter, this is all SUCH FUN! We are playing God with musicians and instruments at our beck and call. We musn't forget to enjoy while work.
