machine quilting

The last few nights I've been in my sewing room have been spent machine quilting the two Hoopla baby quilts on Baron von Quilthausen.  I've been taking a lot of my confidence and inspiration from the professional longarm machine quilter Natalia Bonner at Piece N Quilt.  She does such amazing freemotion work and I wish that I could become even a fraction as good as she is. 

I decided to quilt each one slightly differently.  I'm not sure how well you can see them in these photos:

Sometimes it feels like a labyrinth, trying to figure out a continuous motion design and not ending up on some distant side of the quilt, unable to get back. 

I've finished the central parts of both quilts and began working on the borders last night.  In the borders, I've been using a Mettler thread, and it has broken on me four times now on one quilt.  I'm sure it's a tension issue, but I REALLY stink at trying to figure out tension (maybe that's another reason I love Old Sally - I don't think they had adjustable tension in 1930 when she was built!).  If I don't adjust it, it looks like small loops on the underside with a line of bobbin thread running through it.  If I do adjust it, the top thread breaks.  Part of me wishes for a better machine, maybe one manufactured in the last 30 years, but my conscious keeps telling me it's user error, not the machine.  Any advice?

This is the other reason why I don't do my own machine quilting.  Sigh.