Free motion quilting has more to do with rhythem than precision or spead, you'll get better each quilt you do, and even in the same quilt. Most people move to fast at first and will cause many "toe catchers" (very long stitches). The machines that come with a stitch regulator are usually the "long arm" machines. They will speed up or slow down depending on how fast or slow you are moving the machine over your quilt. The home machine, cannot sense how fast or how slow you are moving so it will set a speed and you need to learn how fast or slow you need to move to get the best stitches. I press down completely, getting the maximum speed for my machine, and I still have to move slower than I want to. I also have a machine that will stitch 1,000 stitches per minute. My point is, learn your own machine and rhythem, don't sweat mistakes (you can only get better with practice), and a finished quilt is always better than one that isn't.
Remember, when first starting a line of freemotion stitching, bring your bobbin thread to the top, and then take 3-4 stitches in place before moving the fabric to lock the threads, and another 3-4 stitches in place when you end, again to lock the stitches in place.
A great practice exercise, and fun too! Is get a piece of fabric, a fat quarter to a yard of easily decernabl :P :P :D e design (Batiks are out.) Use holiday prints, or florals, sandwich them together with batting in the middle and freemotion over every single line on that fabric. By the time you are done quilting that yard of fabric, you will have learned your spead, learned several new shapes, and relaxed enough to do an actual quilt.
Have fun!