I think all of us will tell you the same thing. The only way to learn to FMQ is to FMQ. Practice, practice, practice!!!! Start out with 9-10 inch square quilt sandwiches (top/batting/backing) and squiggle away. The smaller size is easier to manipulate. Do stippling, stars, leaves, hearts, lightning bolts or anything else you can think of. And once you're done quilting them, they make great potholders, coasters, hotpads. I use insulbrite batting or the silver teflon fabric, depending on what I have on hand when I want to brush up. Put a small binding on them. Then move up to tablerunner size, then crib size. If you make charity quilts, practice on them.
I would suggest that you don't start out with anything larger than a crib quilt. I tried my first FMQ with a lap size quilt, and was ready to throw the quilt and my machine away. I felt like I was fighting the quilt and it was winning. My sister, who only makes potholders (she calls them mini-quilts), clued me in on starting small. I'm not the greatest FMQ-er, but I can now handle the bigger stuff.
Good luck.