I always use the natural breaks of the map as my borders;
As Greece I've gone East upto Kotais and Artaxia, using the mountains to protect my line and taken all of Pontiac to the mountain pass at Antioch. So now I can safely attack Egypt. = Pontiac Armenia and Selucids destroyed.
North I've cleared the way to Bylazore and Tylis, = Macadon destroyed
West is all of Italy as far as Massalia and Patavium. All Romans destroyed - horrah.
Now all my borders are secure. and there is a lovely Grey belt across the world.( just need to kill the Germans and Brits to get to the other end of the map. )

Top Tip; Using a stack of horse archers the Greeks get, 1 stack per Area ( 1 for italy, 1 for pontiac 1for greece etc) they thunder around their areas destroying all the Rebels, saving my army for the real work.

Now I Finally have my Spartans !! 1 stack is heading to Carthage to take Africa and Spain. Other stack is heading to Alexandria to move through Egypt.