I have been trying to learn how to fly the Gemini for over 10 years... I still don't get it !
I found 60-75' lines the best for the Zephyr, and 50# line is out of the question. I broke 50# line countless times before giving up. For those light winds, try flying without the weight, no upper spreader, and the bridle adjusted all the way towards the nose. I found it easy to keep the Z in the air in 1-2mph winds, but the tricks don't start until 4-5mph. Lastly, put the kite away when the winds go into the double digits, I know the rating is higher, but it's not worth risking the kite in those winds...