I love scrappy quilts and when I started out I bought a lot of fat quarters. Now I hate fat quarters because they never are "enough"! I moved up to half-yards, then to 1-yard; now I waver between 1 and 2 yards when buying fabrics for the stash. If it's a print I think I'll like for borders I'll buy 3 yards, because that way I have enough fabric to do borders with no piecing.
Solids I buy in larger pieces; usually 3 yards minimum. Some colors that I use a lot I will buy by the bolt if I can find a good deal. (White, Black, Red, and Grey, for me)
Wide backing fabric is another thing I'll buy in large quantities if it's a good deal. I recently bought a bolt of 108" wide navy blue fabric at Joann's for 60% off; came to $4-something a yard...score!
You probably want to hold off on buying whole bolts at this point, though, unless it's a killer deal and it's a good color you'll want to use a lot of!! Personally I like 1-yard cuts to start off; I kind of regret all my fat quarter and half-yard purchases. It's just not enough fabric for me, I love scrappy quilts but that's not all I make and having only a fat quarter doesn't give me enough options.