How to prepare. Well, this could be simple, or this could be hard. If you wanted it to be hard, you'd board up all the windows and live in the basement until you heard on the television that the war was over.
But I find it unlikely that anybody in their right mind would do that. i recommend that you just keep gnomes off of your lawn, and keep flamingoes on. always keep a baseball bat by your front door and one by your bed in case of invasion. you should warn all of your neighbors that have the stupid little creatures decorating their lawns that they are MEAN, DANGEROUS little critters. trust me on this one, friends.
Together, we can kill a gnome.