It really is true that you just have to practice. And it is so frustrating. I started with a smallish sandwich about 6 inches by 18 inches. Then I made a bigger one. I worked on those till I thought I had it down somewhat. Then I decided that I was wasting a lot of thread, so I bought cute fabric to make a picnic quilt for my daughters. I made them about 44 " square. I figured that it was something they would throw on the ground and carry in their car, and would not care if the quilting was perfect. I get to practice and make something useful. I am now ready to bind my second picnic quilt for my other daughter and I am getting better. Not perfect yet, probably never will be.
I have sewn since I was a little girl and I must say that FMQ is the hardest thing I have ever tried to learn. But I am determined to get it down.