To practice I suggest the following:
Pretend you are doing a penmanship exercise. That is if you are old enough (LOL) to have had the pleasure of penmanship in school Do loops, circles, squigglies, worm tracks, drunks walking the straight line......etc. You need to get the feel of moving the fabric to make the design rather than the machine doing it for you. Work to find the balance between the speed of the machine and the speed of your hands. The faster the machine the faster you need to move the fabric.....slower the machine, the slower the hands etc. Some suggest to rev up the speed of the machine to a high slow to medium speed and then match your hand movement accordingly. Some also suggest putting the maching on 1/2 speed if your machine has this feature This way you won't be tempted to go fast. Pretend you are doing a hula hoop motion. Make as many motifs as you can without repositoning your hands. When you need to reposition then stop with the needle down until you get good grip then begin. Don't move out until you have control of the fabric. Let the needle go up and down a couple times and then move forward....And never ever let your hands leave the fabric. some try to dog paddle to keep the fabric moving. This causes one to loose control.
And yes, feed dogs down and darning foot.