If I am doing a small quilt I start close to a corner, and tend to start in a diagonal direction. This is so when you look at it you can not tell the line I followed.
If I am doing a big quilt I start as close to the center as I can (tackle the hardest part first and now you know it can not get any worse than that). I follow a kind of random motion, making sure that I fill all areas as I go to prevent bunching. I try not to concentrate filling one block before moving to the next, because it doesnt look "free" to me.
My opinion only, and I hope it wasn't clear as mud.
The best thing you can do is to practice as much as you can. One thing I found useful was to practice in a whole cloth, preferably of a solid color, so you can see clearly what you did. When I started doing it on quilts I did it mainly on printed, especially flowers, because when I made a mistake it wouldn't show.
Maria