What's the best logical progression of learning music theory?

I learn things best from a logical standpoint - if I know the bare basics, then I can expand on that easily on my own.

For example, learning something like geometry, you start with the properties of a line and from that derive the properties of a triangle.

I already know scales (though I need practice on implementation ;), but where would be a good place to start? The circle of 5ths? Somewhere before that?

Thanks ;)