Alice's link is to the "Paulicy", the bible of OCC. A good idea would be to search CFC and Apolyton.Net for "OCC" and read the threads. There is a good amount of very useful older stuff over at Apolyton.
Basic rule: One City - never another, even for an instant. You are permitted to reload Hut outcomes only if they result in an Advanced Tribe, so save any game before you enter a Hut on grass, plains, or tundra (other terrain will result in Nomad settler instead). If you are attacking a city you may not enter it until it is reduced to size 1, so that it is razed when you enter. Any wonders lost with the city are tough luck.
Conventional OCC is won by spaceship arrival. Part of the struggle is defending yourself from the rest of the world once you launch your ship, if you have not kept them happy with you. A few people have won OCCs by "bloodlust" (are you out there Kev?), usually with special Fundy starts, but it seems to be considered an abberation.
Many play styles and habits you have formed are going to have to be changed. Once the AIs get going you may be reduced to Pathetic on the Power scale, but that can help in asking for gifts from other civs. Read up on such concepts as OEDO years, Tech Gifting your Key Civ, the Super Science City (OCC is all about Science and Gold), bribing NONE units from other civs and Barbs, and Trade. Especially Trade. Paul's page has links to game starts that others liked; you can try making some of your own if you wish. Do not plant your city in 4000BC unless you can see four great terrain specials within your city radius and you have access to the ocean. You are going to have to get along with the other civs, so swallow your pride at their demands and insults. If possible establish embassies or build Marco Polo in order to get the other civs to do some research for you. Trade techs and maps aggressively. Try to stay at peace as much as possible, even going for alliances with nearby civs. If you are shooting for breaking a record you need to start in Deity with Raging Hordes.
OCC is a lot easier on city management, but it stresses all of the perfectionist skills of Civ to the max. You need to know at all times how many beakers you have researched, how many you need to the next tech, how many a caravan delivery will get you, and what the next list of techs will be to choose from. Some techs you will be able to skip, which shortens your list and lowers the cost for future techs (examples: MonoTheism and Theology!). There are some utility programs to help you with this (check out CIV2PLAN and CIV2BEAKERS, as well as SGs HutFinder), but keeping a log is most useful. You will be spending a lot of time with your Foreign Advisor screen, so learn to read it carefully. And get used to building and supporting as few military units as possible.
