I like Leah Day's site
http://freemotionquilting.blogspot.c...5-designs.html because it breaks down different FMQ designs by skill level.
I also watched a YouTube video with Heather Thomas that suggested making a little Quilt Pattern Binder where you quilt 15x15" blocks & then run grommets in one side & connect them with binder rings.
And finally, like Tartan's tablecloth idea, I take some clear plastic (plastic wrap, cut up Ziplock bags or whatever I had around) and draw my possible designs on them with a Sharpie. Once I think I have an idea, I sketch it out with a purple marker.
When all else fails, I ask other quilters, but mostly I avoid that since I haven't mastered very many stitches yet.