The other is to constantly keeping an eye on who has the biggest army.. the computer with the biggest army is the one that it takes the least gold to bribe into war with others. If a computer is giving you trouble you either bribe it into war with others (If it is the one with the top army) or bribe the closest computer with an army bigger into war with it.
This can give a ton of breathing room, in my experience. Besides that it's the usual tricks, science is key etc.

Absolutely this. I've actually managed to win 8-way deity without ever being in a war once by constantly force buying war on everyone that would otherwise have attacked me.