Holding the Yarn
A fellow Fair Isle lister asked about how we hold our yarn when carrying with both hands. Here's how I do it.
I control the tension with my pinkie, by curling it toward my palm to stop the yarn from sliding, or loosening the curl to let it slide. This is exactly the same way I hold my yarn when I crochet, and since I crocheted before I knitted, this was a "gimme." If you crochet, try holding the yarn the same way and see if that works for you.
I control the tension by squeezing the pinkie against the 4th finger to stop the yarn from sliding.