my tip is to slow down - literally. Good quilting is a result of coordinating the speed of the machine with the speed you move the quilt. Slow machine speed with fast quilt movement leads to large stitches and other disasters that require un-sewing. It can also give you interesting designs on the back because of tension issues. Fast machine speed with slow quilt movement results in tiny stitches.
If you have a machine with adjustable stitching speed, drop the speed to the lowest possible and try free motion at that speed. Practice moving the quilt at different speeds while using the slower machine speed. At slower speeds your mind can keep up with the machine and you have more control over the design. With practice at slow speed, you learn to coordinate the movement of the fabric with the pace of the machine so you have more control over the design. If slowest setting is too slow, speed up a little...a little...and practice again.
I've found my "zen" speed and now I can set my machine at the speed which works for me and quickly get into a successful quilting mode.