I booked a guarantee balcony on the Miracle and now have my room assignment. I stil have a balcony room but on the Panarama deck. From what I can see from the deck plans we are real close to Lido deck (food, pools) I just hope it's not to noisy for us.
If you have sailed before make sure your TA or carnival know so you can get an invitation to the past guest party---Free drinks!
They also have free giveaways and drawings for gifts. My husband won a watch. They let him pick anyone he wanted. They still charged him for sizing ($10.00) but still a real nice watch. Also get in the spa drawings you never know you could be next.
If you drink wine at lunch or dinner the waiter will recork it for you if you don't finish the bottle. It saves a little instead of ordering by the glass each night.
I don't know of any "secrets" just these little things you don't want to miss.