My suggestion: 6-1-3-4-2-5, this strategy gives us an early mountain city, ideal for defense aganist TNT, then we get a coastal city, followed by a strong eastern wall of cities, followed by another coastal city, and then ending with an inner eastern wall city. Also, my opinion, is to make sure all cities have at least one unit garrisoned, be it a spear, warrior, sword, tank, whatever, CRULLER- NEVER AGAIN.