2012 Free Motion Quilting Challenge - January

Hello everybody!
This year I am really really serious in trying to improve my FMQ-skills!
I signed up both for The Wednesday Quilt-Along with Leah Day and this FMQ Challenge, hosted at SewCalGal. To me 2012 will be the FMQ-year!
I completed the January tutorial, doing something very small, just a quick sampler with the threads I use in my quilts:

So the red thread is Rayon 40 Madeira, the multicolor one is Cotona 30 Madeira, the white on your left is polyneon Madeira, the last one (it seems white, but it is really a very light green) is Gutermann polyester.
Bobbinfil in the bobbin and a Universal 70/10 needle.

Rayon and Polyneon both stitches beautifully: no need to adjust tension.
Polyester seems "stiff" and rigid and does not curve smoothly.
Cotona was a nightmare, but it was my fault: I decided to try with the same needle, bobbin and tension and this has been a mistake: Cotona needed definitely a different needle and some trial-and-error in the tension department!