The strict technique of the impossible dip is to do a dip with your body tilted backwards, with your shoulders behind your elbows and with your hips at the same height of your hands. In addition, it must be performed without using swing, impulse or momentum. It is a highly difficult exercise but you can work on it step by step. I recommend staying a bit longer in the first levels to prepare the joints, since it is a trick that affects the elbows and if yours are not well prepared, you can suffer joint pain. This is an exercise of maximum strength, so when you are working the progressions take long breaks.