Great advice above. I agree with the tape on the machine and shortening your stitch length. Without seeing pictures of where the stitching is coming out, I'll guess it could be at the beginning and the end of your sewing. Try Leaders and Enders (as Bonnie Hunter calls them) or Spiders (as Marianne Fons calls them)! That's where you start to sew on a scrap piece of fabric and continue on (without out cutting) to the good fabric you need to sew. I use LOTS of spiders...they're all over when I'm sewing.
The WHY? I think you can call the '1/4" seam' a Standard - like 8 ounces is a 'standard cup' measurement. Imagine the difficulty of making a cake using different sized 'cups'. What would happen if the instructions said '1/2 a coffee cup'...Would I use the 8 ounces, 12 ounces or the 20 ounce mug?
There's LOTS of practice ahead of you! Enjoy it ALL!
Nan - IN