Work your way to the top of the wave just like a flat spin. Once you are there wait for the boat to begin to accelerate down the wave. There is a small window of opportunity before you will stall out, so be ready.
As you begin to accelerate, extend your paddle blade to the opposite side of your boat over the bow. Reach out far enough as to not interfere with the spinning of your boat as you start the spin, but not so far that you are fully extending your arms and shoulders (this can result in serious shoulder tweekage). Keep your elbows slightly bent. Dip the power face of your paddle blade in the water at about a 45-degree angle to the downstream current. If the wave is steep and fast, you will want to quickly initiate a spin and pull your paddle out of the water. On flatter waves, such as the one pictured here, keep your blade in the water slightly longer and lead your boat around with it until you have enough momentum to complete the 180.
Remember to keep your boat flat or angled slightly down the wave. When attempting this move it is easy to lose your plane by giving the boat too much downstream edge.
As you reach the back surf you have a decision to make. Either finish off the 360 with a draw stroke like a normal spin, or keep your boat flat and rotate you body around for the clean!
