The concentration ratio of acetate to acid has to be 0,549 to 1.
This means that you have to prepare a acetic acid solution and a sodium acetate solution of equal concentration. At best of the concentration that your buffer is supposed to have.
And now mix acetate solution and acid solution in the volume ratio of 0,549 to 1.
You can also prepare more concentrated stock solutions of acetate and acid,and then dilute them, but then keep the ratio also at 0,549 to 1.