If I like it I buy a yard...
If I love it I buy three yards...
If I can't live without it, I buy the whole bolt...
I usually buy lots of neutrals, blenders, solid, and non themed fabrics just to have on hand. As these will not go out of style and as you will notice neutral get used up alot.. I'd never get less than 1/2 yard cuts unless or was all they had.
Start with a color and build on that.. Then work on the next color. Bit seriously it will not take long to build a stash!!