I'm not familiar with this particular thread. Are you threading the needle with the end that comes off the spool, so that the knot is on the other end? Threads have a directionality to them (similar to hair), and they are less likely to knot if you are sewing in the direction that lays the fibers flat.
The thread may be just too soft. A stiffer thread is less likely to tangle when hand sewing. This is why hand quilting thread is so much stiffer than regular machine sewing thread. Instead of a conditioner, try running the thread through beeswax.