Usually I fall in love with a pattern and then seach for the material.
For instance I saw a pattern, fell in love with it and then decided it would be great done in black/white. So I have been on a mission to collect black/white, white/black fat quarters to make it.
But..on the other hand, I fell in love with civil war repro fabric but have yet to find the right pattern for it.
There is no right or wrong, just what you want :) And I have been quilting less than a year but closing in on my anniversary :)