Help, my googles fall off or leat at jump

After two years of swimming I decided I'm ready to experiance how it is like to take part in a swim meet. OK, I accepted my name will be o the bottom of results list, but I don't care, it's not a problem. The problem is that today I decided to train jump in the water. I never did it before and I'm in sort of a panic. Googles fall off or at least they leak so much that its not possible to swim. I have two options: - jump in the water on foot and start swimming - practice regular jump Ok, there is also a third option - not to go to the meet, but this is not an option for me... Is there a hope that there are simple rules how to avoid googles falling off or leak, or I should abandon hopes?