You can put it in a plastic bag a swing it into a hard surface like a counter top or a cabinet door. They are not that hard to knock off they are only mice. Now dont swing too hard or you might get a mouse pancake just enough to make a thud. The mouse will twitch but that is just nerves. Use some hemastats or some tongs and dangle the mouse in the enclosure and they will go for it. DON'T EVER USE YOUR HANDS TO DANGLE THE MOUSE OR RAT. Otherwise thats about it.

You can thaw out a frozen mouse by puting it in a ziploc bag and seal it up. Then put some hot water in a pot or bowl and float the mouse or rat in it. Replace the water every 10 minutes and it will take about an hour to thaw it out completely which is very important because the animal will start to decay in your snake's stomach before the center it thawed out.

I feed Prekilled and have never had a problem. At times where a snake wont eat you can put the mouse in a ziploc bag and feed it frozen/thawed later. Its a good way to save money.

I am sure there are many ways to off a mouse but i found the above to be easiest.