I am fairly new to quilting too, and I started off buying one yard. I learned fairly quickly that a yard is not enough for what I want to do. I usually want a border or binding made of one of the fabrics in my quilt top. One yard doesn't allow for that, or at least it doesn't for me. I now buy a yard and a half or two yards.
So far this has worked well for me.
My stash recently grew at a Hancock;s sale. The sale is still one, if you have one nearby. Most of what I bought was 40% off.