I've never had luck with the "tube" method of making bias binding so I usually do the same as the last posting. I use my ruler markings...line the 45degree line on a straight edge of the fabric then make a 45 degree cut on the fabric. Fold the fabric so those bias edges meet... then continue cuttiing my strips the desired width by lining up the ruler on that edge. I find that it REALLY helps to starch the fabric prior to any cutting.
Hope this makes sense!!!