Well I play on Classical start. That helps the AI not economically crash but it may also ensure that the cottage happy AI is always struggling to get stuff built. I also play with between 12 and 14 civs on a standard map. You would think that would make them more aggressive but who knows. I play with 10-20% peak softening on Erebus. 0% peak flatening and you can just park some archers in a hill fort forest chokepoint with a river in front of it and no one will ever be able to touch you, the game kindof becomes a joke. Keep an eye on the map. If a civ runs out of room to expand it most likely WILL fight someone, even if thats a bad idea.
HAVE A BIG ARMY AND A BIG SCORE. Elves and Lanuan are good at this (big cities) and just plain good in general. Scions, oddly enough, are good at having a big score thanks to the Risen Emprawr's free creative and pop 1 city spam.
Trap an elephant within your borders. Spend the next infinity turns shooting at it with archers. Poof, infinite heroes. Combat V Drill IV archers fortified in a walled border hill city makes war more of a massacre anyway.
Don't declare war on people, especially if people like them. Don't give in to cancel trade demands unless it would push you into cautious/annoyed with someone, or unless the target is irrelevant.
Be a good or neutral civ it, it makes it easier.
Either plan on getting FoL/RoK and starting a lovefest or be agnostic for the lack of religious demands. Being not agnostic works ok too, you just get religion demands from time to time.
Rush hard for way of the wise, give that to everyone, and try to get them into the ubercouncil. Yea, they will make you run liberty and ban death mana, ohwell don't run death mana. Give Way of the Wicked to people you want on the 'other' team.
Open borders with everyone and maintain a big army, OR don't open borders or trade maps.
Give people mana if you want goodies or want to make them your friends. Civs pay for that stuff by the gram, yet its worthless for the half of the game that counts. Even once you have mages its like "look at me, I have maelstrom. Its like an archers ranged attack but not as good."
Think of tribute demands as delicious diplomacy cookies. Reject them if the demanding civ is a looser or the -1 hit wont affect relations, otherwise give in to them (except dangerous military techs...) If an evil civ doesn't like you, keep 250-300 gold in the bank and guess what, they will demand a small quantity (70 or so). Kindof expensive for a temporary +1 tribute/+1 fair trade but its a gateway to borders and tech and goodies trade.
Trade around magic techs freely, they actually hurt the AI because they cant use mages.
Keep people busy, to the extent that you can. Getting people to declare/cancel trade with others can be hard, but can also pay off. Also, give builder techs to builder civs. Guess what happens when you do? They build stuff. Aqueducts cant march into your lands, thus you are eating their hammers. Play with the WB to see what civs build what and when.
If you want to be really tricky (and you do) give death/entropy/chaos mana to someone you don't like and who doesn't like you. Not only can you make them happy, while getting trade goods, other civs will hate them for having it. Evil manas are hot potatoes though, be careful not to hold them for too long. Also, it sucks when they get banned.
