Over the years I have found the importance of a correct SCANT 1/4" seam, so here are my tips, for what they are worth.
If you have one always use the single hole sewing plate.
Remember the scant 1/4" should include the width of the thread and I do find since changing to Aurifil thread 50 I have much better seams that lay flatter.
A well maintained and clean sewing machine, especially the bobbin area
A good 1/4" patchwork foot, PLUS a seam guide is the "belts and braces" option for me
And remember a SCANT 1/4" seam it is only a measurement so if you can do a 3/8th seam or any other measurement you can do it, just remember what it is a 1/4" that includes the width of the thread.
And of course good needle frequently changed, never skimp on needles