As mentioned by everyone here...DON'T start on a quilt! Make practice sandwiches and keep trying until you get it right. The biggest problem I had was getting my tension set right for my machine to keep from having eyelashes and nests of knots on the back.
I found my tension had to be quite high on the needle thread to keep the back from looking a real hot mess. Once I got everything worked out, I kept the practice sandwich that looked the way I wanted on front and back. I wrote on it with marker to note what my tension settings were, what sized needle I used and even what thread I used. When I am ready to FMQ something else, I grab another practice square of material from my current project (if possible), set my machine as noted on my successful square, and make sure that everything holds true.
THEN I will FMQ my piece.
It's a few extra steps, but, it sure beats picking FMQ stitches out of a quilt!!
Good luck to you!