I practised for about 5 years (off and on) before I got the hang of it (I also bought a brand new brother dreamweaver, which I am sure helped).
I swore about 2 years ago that I was done with FMQ and would never do it again. But ... you know the quilt of the week on the home page? That's mine! And I am darn proud of it, because I busted my butt!
I hate meandering / organic FMQ. Drives me bonkers. I used stencils and lots of them. I mix and match and make up my own designs.
Start small - 20x20 - but make the fabric 30x30 so you have edges to grab onto. Do feathers, big circles, swirls and loops ... they are easy and if you mess up, it just looks like part of the design (trust me!).
Once you are confident in your movement, do a black thread on white fabric ... or the reverse. This helped me find my weak spots. Once I practiced those and got them down pat, I was off and running.
Do you know what my practice quilts were? lapquilts for my friends' cats. She loved them! She laid them all across the back of her couches (she got about 20 of them) ... the cats love them, no more fur all over her couch, and I got to practice. Also, I used all my scraps because the cats don't care!
Have fun!