Now I don't know if anyone reading this is familiar with James Webb-Young's little book, perhaps lots of you know it. For that matter I don't know whether the technique he describes is taught in college. I didn't discover the book until I'd been working for years, which is a shame because it's ace. And here's the fundamental principle around which he presents his technique:
JWY goes on to suggest a system for collecting and ordering the stuff you collect. I found adopting it, a) encouraged a more systematic and varied collection, and b) keeps it all together so it's easier to find later. His Technique for Producing Ideas goes further and has proved invaluable.
The combinations thing goes for everything we do: On one level we combine colours with shapes and typefaces and words, and end up with logos. On another level we take an airmail letter and the idea of love songs and think about love letters, and end up with things like this, despite who the client is.