Some machines will also allow you to release or adjust the downward pressure of the presser foot. This is very helpful -especially if you are covering rather than dropping your feed dogs.
Try writing your name! Then try loops (like a string of cursive e's) and coils.
Think of it this way - you are drawing a picture, but instead of moving the pen (needle), the pen is stationary and you are moving the paper (quilt) underneath it.
It also helps if you can push yourself to go a little faster (foot pedal) than you think you ought. When the machine is running slowly, it's hard to get graceful curves.