Cut your thread length to no longer than about 18ins (45cm). This should reduce your knots. If you still get the occasional knot in your thread, use the tip of your needle to loosen the knot slightly and then pull the thread firmly. If this doesn't work, cut off the thread below the knot and start again with a new length of thread. As you stitch, your thread will become twisted so, every now and then, let your needle hang down and the thread will naturally untwist itself.