Your strategy should depend who you're next to, but even with non optimal play, you should be able to survive on king. I understand your pain though. Quickly after my first win on immortal, I jumped back down to prince just to see how much I could dominate with the mayans. I went fast national college and Attila killed me . Try to create a couple of scouts to open the game if you don't do that. The really fast national college strategy only works if your nearby civs are relatively peaceful ones. If you find yourself next to Shaka or Attila (or any of the crazy guys), you'll need to get a few composite bowmen really quickly to fend off their attacks (and delay the national college accordingly). Try to place your cities on hills for better defense, especially if you feel like they are going to be under attack soon.