GimliLegolas
Chieftain
Apologies if this has come up before. A strategy I have used a lot recently is to trade luxuries/strategic resources and gold for AI cities and then almost immediately declare war. It is important in the later part of the game as a way of looting works of art/music etc and it really messes up the opposition.
Prerequisites are that you have a strong economy with a good number of luxuries and gold per turn. I make sure also that I have a good cushion of happiness and that there are no trade routes to the Victim. I start by picking on the next to weakest Civ. I try to trade for either their third city or any number of their smaller cities. Once a deal is reached I declare war, strip out any great works, raze the city, sell the most expensive building and then - unless the city has a wonder or access to a resource I need I sell/give the city to the weakest Civ (who might raze it or give it back to the owner) so to not have too much unhappiness. After several turns the victim will sue for peace and might give another city. You will have to accept diplomatic penalties eventually.
Prerequisites are that you have a strong economy with a good number of luxuries and gold per turn. I make sure also that I have a good cushion of happiness and that there are no trade routes to the Victim. I start by picking on the next to weakest Civ. I try to trade for either their third city or any number of their smaller cities. Once a deal is reached I declare war, strip out any great works, raze the city, sell the most expensive building and then - unless the city has a wonder or access to a resource I need I sell/give the city to the weakest Civ (who might raze it or give it back to the owner) so to not have too much unhappiness. After several turns the victim will sue for peace and might give another city. You will have to accept diplomatic penalties eventually.