Hello Glenn!
The prevention would be to cut the decal out of the sheet with a small piece of backing paper - maybe leave a paper "tongue" on one side to have something to hold it by. The decal is then soaked and taken out of water while I'm waiting for the decal to become moveable. This way the decal doesn't get a chance to separate from the paper. Then I put the paper on the model close to the place where the decal ultimately goes. There's some water on the model there, but not enough to form a big drop. Then I slide the decal from the paper directly to the model surface. I move the decal around with a toothpick or tip of the tweezers.
....
Paweł