Always good to start with a practice sandwich. Even pros will frequently use a practice sandwich. I prefer to have the feeddogs in the down position and use an open toe free-motion quilting foot. Certain threads are also easier to use than some threads for free-motion quilting. I do like Sulky, but have had a wee bit more problems than using other threads. For FMQ my favorites are Aurifil or Superior Threads 40 or 50 wt cotton threads. To clarify, I do use others, but those have been the easiest for me to work with.
And, today I posted insight on a very good free-motion quilting book that is an excellent choice for those learning to do FMQ.
Some instructors say practice, practice, practice. Some say repetition (e.g. do the design ~10x and you'll have it mastered).
Enjoy!
SewCalGal
www.sewcalgal.blogspot.com