Be sure to use a darning foot (or free motion quilting foot).
Use a brand new sharp needle, ie top stitch, embroidery, or microtex work well.
Check that the thread, needle, and fabric are compatible--Caution, the needle eye should be the right size for the thread weight.
AVOID old or bargain bin thread!
Be sure to drop or cover the feed dogs.
If your machine has it, use the needle down feature.
You may need to adjust the tension for FMQ--I have to tighten the bobbin tension a little to keep the bobbin thread below the quilt surface (so I bought a special bobbin case and set the tension for FMQ and that's all I use it for.)
Lots of web sites that talk about how to free motion quilt. Then, it's PRACTICE, PRACTICE, PRACTICE! I use a portable white board and draw free motion designs on it (while watching TV, etc.). The idea is to get it fluid without jerking, jumping, speeding up or slowing down, etc. When your hand and brain are able to work smoothly, then you can probably do free motion quilting. Practice on scraps of fabric and batting (preferably the same kind you will be working on). Cut up some 14 inch squares of fabric and batting and draw designs on them and see if you can stitch them. Some advice: don't watch the needle...look at where you are going in front of the needle. Don't expect perfection to happen overnight. Many quilters have been FMQing for years and still make mistakes. (I've made a few quilts and my stuff still looks less than professional, but it's all mine!) Free Motion Quilting with Janome 1600P sewing discussion topic... All About Needles