I don't milk, so I'm sure others can answer this better, but from what I understand from reading transcripts of some of Moonsinger's games, you basically keep your civ within a few tiles of the domination limit, and then build as many cities with as high a population as you can. The earlier you get started on this, the higher your score.
The best map settings are probably huge/8 civs/arch/60%/wet/warm/5 billion. A 60% arch actually gives a few more tiles than a pangea, which lets you cram a few more cities in there.
Use Democracy for late in the game, as the cash rush is vital to build Aqueducts and Marketplaces in every one of your towns. The Pyramids are very useful for a pangea, and Longevity doesn't hurt either. (you don't have to control the Pyramids from the start, but it'll just about cut in half the amount of time required to grow, so in the milking stage you want it).
Read over some of Moonsinger's games, and you'll get a pretty decent overview of the milking techniques.