|This is actually a tip I learned from Sandra Betzina's "Sew Perfect" show on TV. (I miss that show!)
To keep your thread from knotting easily before hand-stitching, run it through beeswax. You can get the kind for sewing at Wal-mart for less than a dollar. You may have already known that. What you many NOT have known is that if you run a warm iron over it quickly after running it over the wax and before stitching, it makes the thread even more durable and you won't have a problem with it making irratating little wax balls on the surface of your fabric as you stitch.
If you've never used wax in your hand stitching, you will wonder how you got along without it once you start.