A few things that might help you loosen up -- remember to breathe! When we concentrate, we tend to hold our breath and that can make our work less flowing and smooth. I like to put on some music and hum (or sing) along. That keeps me breathing and my quilting smooth and even.
Use something to give you grip, like Machingers gloves or, if you don't like gloves, a trick I learned years ago from Diane Gaudynski is to use Neutrogena hand cream (the kind in the tube). When you use just a small dab on your fingertips and palms, it makes your hands sticky and you can grip your quilt better. (I have a tube I bought about three years ago and it's still probably half full - you really do only need a small dab and yes, it works great!) I love my Machingers, but I still often use the Neutrogena cream when I just don't want the gloves on.
And if all else fails, try a half glass of wine before quilting - it can work wonders!
