I always tighten the lower or bobbin tension up a bit. I keep a separate bobbin case for this purpose. I also speed up the machine as well. I don't know if you can speed up your machine, but since you are just new to this, speeding up the machine and you sewing more slowly does help with the spacing and length of the stitches.
But really, the only help is for you to continually practice practice and practice some more. When you do get it, you wonder how you had such a problem, because it is not hard. But to make feathers and do other fancy patterns is nothing more than practice.