In my first few games I thought you actually had to bring a level 4 unit into a city to build Heroic Epic there.
Though I play on monarch and win so I'm clear from the noob status but I still got noob issues.
Don't understand espionage points, if i get a great spy it just sits in a city till the end of time. No idea how to deter spies from poisoning wells.
Never have built corporations yet. Everytime I try it seems to never work.
things I use to do everybody has already mentioned, especially civics like mercantilism and decentralization, using a fortress to utilize a resource,
When i first played Civ 3, i thought you actually had to build roads to bonus resources. and i thought how the hell were you supposed to build a road to fish?
thankfully those days are long gone...
To deter the poisoning of wells and similar such things, train spies and put one to sleep in each city. It will watch for foreign spies, decreasing their success substantially.
Use your first Great Spy to build Scotland Yard. Beyond that, I don't know what they are good for either.
If you can't build corporations, assuming that you have the needed Great Person and tech, it could be that you are in either Mercantilism or State Property. Both prevent the building of Corporations.
I thought galleys and WBs can't enter ocean tiles, period. I only later realized that they indeed can, if the said tiles are within your cultural borders. (IMO, this should have been mentioned in the in-game description of the unit).