Anyway, I mentioned in my last post that the monster quilt that I made for my husband really forced my hand at learning how to sew an accurate 1/4" seam. Knowing what I know now, I consider this the first thing you must get some consistency with when learning to quilt.
The first lesson I had to learn was to slow down. At least with my machine, if I get going too fast, the fabric will tend to shift left. Do sewing machines get front end alignments?
There are tons of methods and tools out there. Some machines have a special foot, and I've seen a magnetic guide you can buy, but I just use tape.
I bring my needle down on a ruler right at the 1/4" line.
And then I just lay a piece of blue painter's tape beside the ruler. Painters tape is a tool I use pretty often in quilting. It leaves no sticky residue when you remove it, so I use it for holding the backing in place when I baste, for marking my sewing machine, and for marking rulers when I need to. You can just take it right back off & not worry about having to clean the surface.
Now, this method does produce an accurate 1/4" seam. But you should know that with the more intricate patterns, what you really need is a scant 1/4" seam. The 'definition', if there is one, of a scant 1/4" seam is 1/4" less 3 threads. But, the thickness of the fabric can come into play, as well as the thickness of the thread, whether you iron your seams to one side or open, and how you press your seams in general. The only way to be certain is to accurately cut 3 pieces of fabric in 1 1/2" widths, sew them together and then measure the center piece to be sure it is exactly one inch. And this must be repeated with each project.
When I read all this, I was thinking 'you've got to be kidding me.' I have since learned that quilters do not kid about seam accuracy.
As with most things in life, I think you need to only take this as far as you need to. For my current projects, everything is lining up just fine with my current method. I have a much more intricate pattern in mind for sometime next year, with stars inside of stars, lots of half-square triangles and flying geese. For that pattern, I will go all out to be sure I have a true scant 1/4" seam and all my points match up.