I've played Civilization V for over a year now and frankly the default strategy for me is build up relations with militaristic city-states and conquer at will
Some of the city-states I have met (and sometimes conquered):
Cultured[]
Maritime[]
Mercantile[]
Militaristic[]
- All but Dublin, Edinburgh (Civ5), M'banza Kongo, and Sofia
Religious[]
- All but Ife
I have played as or encountered every single civilization except for the Indians and every civilization in BNW