I don't know if this has been brought up before...
Just noticing that in a sequential game, whoever gets the first turn has the advantage of getting 6 armies to begin with, and being able to attack first. If he attacks and successfully takes a territory of the second player on the list (for example), that player only gets 5 armies, yet that player hasn't been able to deploy anything or fortify at all. One missing army (or sometimes more) can make a huge difference in the first round of play.
Anyway, one solution would be to give all players 6 armies during the first round, regardless of territories controlled. Then, the regular rules apply after that first round.