I've been a diehard Civ player since Civ 1. I've only played in 2 Civ world games so far (i wasn't in the closed beta), but I come to share my experience and advice. I realize that the game is full of casual (and cluless) players, and many of these tips wouldn't be possible without them in the game. Some of these may be somewhat exploitative in nature, so maybe we can discuss the need for change.
2 man, Interior Minister abuse(?)
This seemed fairly obvious to me the first time i saw the mechanic. I tried to find some discussion on it but I was unsuccessful. Basically you and your cohort team up and bank harvest, until one person can take Interior Minister (by building a Ginormous Granary for example). You should be able to do this with starting resources/working the market/bubble popping fairly easily. Interior minister then uses all harvest giving the other member an equal number of free harvest. 2nd member then takes Interior minister and repeats the process. With the proper tech planning, this can go on for a very large number of harvests. Even without it is relatively simple to get 3-4 iterations pretty painlessly.
The concept still applies for 3-4 person civs, it just becomes less efficient.
next post - Science Maze (i realize this is going to get really long, so I'm breaking it up)