I like playing as Sparta but my main problem is I end up losing Heraclea and Kythera. I try and build up as many naval forces as possible in Kythera but I am attacked endlessly buy at least 3 other factions who have better naval capabilities than Sparta. The same goes for Heraclea, typically my forces there are small and I am attacked by 3 other factions.
What areas should I focus on?