I watched a TON of Leah Day's videos and I did my practicing on potholders and place mats! I'm not great at FMQ but it doesn't terrify me anymore either. I still need a LOT of practice before I would do it on an "important" quilt, but quilts that are just for me are perfect for practicing on. I even managed to FMQ a king size quilt! (And I don't have a longarm machine....yet)
A tip that helped me a lot - make sure you have good support for your quilt as you're working. If too much of your quilt is hanging off the table it can pull itself along faster than you want it to and it's harder to control. Grippy quilting gloves helped me quite a bit, too.