Re: Naval Battles
This advice is good. I'd like to suggest another option for barbarians. The TWC Wiki says, on its useful Cultural Groups page, that:
Barbarian Cultural Group factions are the only factions who are able to gain special naval units from captured ports of other Cultural Groups, and only if those ports are not converted to your culture.
As I understand it, barbarians can recruit different naval units from captured, unconverted ports of different cultural groups. At some point, I'd like to play a barbarian faction and capture an upgraded port from each of the other cultural groups, to see what sort of navy I can build.