More ideas from Dana
Tension tips - I've been looking for this all my life, I think :) - This will be so helpful! I have just always called Elizabeth! Thankfully she pinned it too - *smile*

When a “bird’s nest” of thread appears, the likely culprit is your upper thread tension. If loops appear on the underside of the fabric, the upper thread tension may be too loose. If knots appear on top of the fabric, the upper tension may be too tight.