Learn to spin your poi both forwards and backwards and be able to transition from forward spinning to backward spinning using a pendulum stall. This is basic poi spinning material, but is invaluable in the control that it will add to your poi spinning.

Play with all the variations you can think of; both poi forward stall right, stall left, both poi backwards, stall one, stall the other. Stall both, reverse direction on only one.
Play around and see what you can learn with your poi.