Working in Variation Form

Hello everyone, I'm new here.

I've recently been studying the Schillinger System of Musical Composition, and to apply what I'm learning, I've decided to compose a set of variations over the course of time that I'm studying this system. As of now, I'm planing on using a theme from Bernstein's On the Waterfront (the opening horn theme played in this video), and using just solo piano (though, since Schillenger also discusses some Orchestration techniques, it might be a better learning experience to score it for multiple instruments, but I'll decide on that when I come to it).

My question involves theme-and-variation form. Most forms seem to "map out" easily the processes of introduction, development, restatement, tonal movement, etc. which a composer may then work with in his own way. Variation form seems to be much less rigid in these aspects, and thus for an inexperienced composer, it is a bit harder to think about in terms of large-scale structure.

So, my basic question is what sorts of formal techniques would be helpful to consider when first considering the larger structure of a Variation form?

I really appreciate any help!

Well, I don't consider tonality to be the center of any form any more. So, I'm going to just ignore that aspect of your inquiry.

When writing a theme and variations though.. the main things I would look at are:

1. Viability of the theme: How many ways can you variate it? How inventive are the possible variations?

2. Once you devise how many variations you want, then you can look at how do you want to transition? Will you do as the classicists and cadence after each and every variation? Or perhaps will you add transitional passages where the variations morph or merge into the next variation? Lots of options here.

3. Overall Structure: just stating variation after variation may not get anywhere. This is where you can look at how you want to pace the variations you've come up with and decide whether or not you want to rearrange them. Perhaps one variation would make a great climatic point? Perhaps another variation would do good as sort of a coda?

That's pretty much the things I'd look at. Like I said, these three points are easily done without any sort of tonal understructure - though, I suppose if you want one, you could add that as the fourth point. But, in this day and age, I don't really see that as being anything pertinent to the overall form.