Good responses so far.
I agree, it is vital to have your quilt sandwich rather loose in the hoop. I've broken needles before if there isn't enough slack.
I almost always use Hobbs Heirloom batting (80% cotton, 20% polyester.) It's thin enough to quilt easily, but since it is 20% poly, you don't have to quilt extremely close together. Wool is also a joy to quilt, the needle glides though like butter!
I've been quilting for nearly 30 years, and though I am machine quilting a little more lately, my first love is hand quilting.