There have been egalitarian militias in the past, from which we can learn important principles to apply in creating our own egalitarian militias. These principles are:
The members of the militia are volunteers, not conscripts. They can leave the militia anytime except during a battle.
The members of the militia elect their officers and can recall them by democratic means if and when they wish.
The officers are authorized to give appropriate military orders and commands that must be obeyed during a battle, but they have no other privileges and wear no special insignia of ranks.
The entire membership of the militia, as equals, democratically determine fundamental goals.
These principles, in whole or in part, were applied by peasants in the German Peasant War of 1525, by peasants and other working class people in England in their New Model Army in the 1640s, by the American revolutionaries in the Minuteman militia in the 1760s, and by workers and peasants in the anarchist militias of Spain in 1936-9.
Interestingly, pirates had a very similar kind of democracy that you can read about here.