If it's a fabric I really love, I buy at least 3 yards. The rest of the time I just get a little more when I buy a fabric. If the pattern says to buy 1/2 yard, I buy 1 yard. I have been amazed at how quickly I have begun to accumulate fabric that I really like. The main thing is to buy what you can afford. Quilting is an expensive hobby. You would love and enjoy it and not feel guilty because of the money you are spending.