All I can say is: you have to be ready! The first time you put on your gear, it will feel horrible! You will not be used to that much weight. when you get in the water, you will be scared and excited. The thrill of breathing underwater will astound you. The pressure from your gear will be gone and you will be introduced to a brand new glorious feeling, a feeling that can't be explained. You will feel anxious and be ready to respond to your instructor. watch the signals your instructor shows you, and do the best you can. don't be afraid to tell your instructor if you can't equalize or don't understand.Relax, learn well, dive well, and remember, the confined water dives are just the begining!
And MOST of all- HAVE FUN- that is the point of the sport!