Here is one big problem: Nobody wants to start or join a Constitutional Military due to fact that the Media Leftist Militia have so successfully marginalized them in the ramp up to martial law. And believe me martial law is what the left are after because in America there is no other realistic way in terms of a check mating move.
"joining" any "group" is a death sentence. The first up against the wall will be the leftist radicals, followed by all the "Oath Keepers", "Militias", whatever patriotic group you THINK is going to make a difference.
Just make sure you educate your family. That's going to keep them and you alive. Learning skills that will be useful in medicine, outdoor activity, crafts, farming, mechanical and electrical work... etc...
When the time comes it'll be to late to prepare. Read "War of the Flea", "On Guerilla war", "Out of the Mountains". Just for information purposes of course.