If going more than gliding distance to at least the shore line then have life jackets available and know how to use them and put them on under pressure. The lower you fly the less time there is to put a life jacket on
Wen the emergency occurs, particularly in a single engine, it's a bit late to be thinking about donning a life jacket, if planning over water flight don the jacket and adjust prior to entering the cockpit.You can't foretell the emergency or circumstances that may put you in the water, if you're not wearing it you wont be getting out of the cockpit with it.