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There is no real science to it. First off, make sure the fish you are grabbing by the mouth is not a species with large teeth (musky, walleye, shark perhaps). Also, be wary of what type of lure you are using. It is very easy to snag yourself on a treble hook when lipping a fish. Other than these two considerations, IMO you dont really have anything to be scared of. Once you catch a few and get some practice, all will be right with the world....
Happy fishing, Enjoy