Okay so last night after several hours of play (significantly less this time around) I was able to reach the two ultimate endings, world domination and space race, by 2004 AD. Was set for a small pangea with three computer AIs. And here are the secrets I learned:

1. Expand as fast as possible, if you have a city larger than 5 and you have fewer than 20 cities (on a small continent) you better be building a settler unit.
   
2. Suround your enemys and try to keep them from getting land to build on, build on it first.
   
3. Don't go to war till you have signficantly better tech so as to not waste units. You can expand or you can build military, the former seems far more effective in the long run.
   
4. Don't waste your production on dead end units, in other words don't build warriors, swordsmen, or horsebound units in any quanity. Build spearmen, they can be upgraded all the way to mech. infantry (the cost of an upgrade is very affordable in comparison to the production costs).
   
5. City improvements are well worth the amount they cost (marketplaces, banks, and courthouses make you much more money than they cost).
   
6. Wonders are priceless, build as many as you can as fast as you can, but make sure it doesn't slow down your expansion.
   
7. Change to a high production government as fast as possible, republic or democracy.
   
8. Increase science funding to 60 or 70%.
   

And thats all I can think of at the moment. Its a fun game. Now I can go back to a higher difficulty and see if it kicks my ass again.