I would like to initiate a discussion on the land improvement strategies, as this seems to me one of the chief improvements of Civ4 over its predecessors (where you basically had 1-2 basic choices for each tile).
I think broadly speaking there are three main strategies of doing so, each of them achieving the best synergies with different game styles, terrain improvements, leader traits and civic choices.
I. Rich Suburbia ("Modern US")
Chief terrain improvement: Cottage
Best traits: Financial (even more commerce), Industrious (wonders mean great people so you are overcoming one of flaws of this system), Expansive (health means bigger cities, so you are overcoming another flaw of there being not enough food)
Civic choices: Universal Suffrage, Free Speech, Emancipation, Free Market, Freedom of Religion.
This strategy relies on building cottages, waiting for them to develop into towns - and raking profits of their commerce.
Advantages:
(1) flexibility (non-Financial civs, with all the above civics and Printing Press tech will be getting +7 additional commerce per town, more if they are Financial; this means extra gold to buy buildings - Universal Suffrage allows that and extra science and culture);
(2) steady progress (you are maxed to gain a steady growth in both science and culture, with a stable increase per turn).
Disadvantages:
(1) not many great people (your food production will be rather low, meaning you won't be able to afford many specialists);
(2) hard to rebuild (if enemy pillages your towns, it will take many turns - half less with Emancipation, but still - to grow it back).
Best suited for: traders and peaceful expansionists (with Freedom of Religion you will give other civics one less reason to hate you). You will be able to found many cities and maintain a relatively large empire, while buying resources from other civs. Diplomatic victory is probably the easiest here (and with the UN under your thumb you will be able to force your liberal tyranny on others mwhahahaha ). Also, possibly the easiest way to achieve "score" victory.
II. Specialist Heaven ("19th Century Germany")
Chief terrain improvement: Farm, supplemented by mines
Best traits: Philosophical (even more great people), Creative (even easier cultural victory, helps keeping people happy), Expansive (bigger cities)
Civic choices: Representation, Free Speech or Bureaucracy, Caste System, Mercantilism, Pacifism
This strategy relies on specialists - and farms to feed them.
Advantages:
(1) lots of great people - you will be having tons of them, especially if you are Philosophical, meaning you will be able to rush buildings, speed-up technologies, run trade missions for extra cash or drop cultural bombs.
(2) small is beautiful - this is the most "build up" strategy - you will be much better off having a few big cities than a lot of small cities; this means less maintenance costs, easier to defend etc.
Disadvantages:
(1) "choppy progress" - unlike the Suburbia tactics, you won't be getting a steady growth here, but rather big leaps whenever you get a great person followed by a relatively stagnant period of waiting for them (compared to the Suburbia strategy at least).
(2) low disposable income - again, unlike Suburbia, your main resource are great people and they are somewhat unpredictable (yes, you can influence the chances of getting different types, but you won't have as much flexibility as Suburbian civ in using them). This means you will also not have much spare cash (unless you run a trade mission with your Great Merchant). And having Mercantilism will hurt your trade income somewhat.
(3) hard to mobilize for war - between pacifism, free speech and not maxed up production, you will have a rather hard time staging a succesful war against someone - sure you will be able to defend well, but only if you hole up in your cities and wait for the enemy to go away.
Best suited for: Cultural perfectionists. You will be able to spread your cultural borders a lot, and even capture foreign cities by cultural flipping alone. Cultural or scientific victory the easiest here.
III. Industrialized State Property ("Soviet Russia")
Chief terrain improvements: Mills, workshops
Best traits: Organized (civic choices are expensive), Spiritual (you will want to change civics often between war and peace economies), Aggressive (in the sense this strategy being useful for a militarist), Industrious (you will zap most wonders).
Civic choices: Police State (for War) or Hereditary Monarchy (for Peace), Nationhood or Vassalage, Serfdom or Slavery, State Property, Organized Religion (for Peace) and Theocracy (for War).
This is a strategy for those for whom peace is just a preparation for war.
Advantages:
(1) High productivity - thanks to state property you get extra food from workshops (normally a production-generating improvement), which normally reduce food - meaning you can build them on many tiles and still maintain enough food to feed your population. And Organized Religion will grant you even more of those precious hammers.
(2) High military power - between free units under Hereditary Monarchy and unit production bonus under Police State you will be able to build many units - and you will want to do so, since in peace they will (under hereditary monarchy) make people happy, and with Vassalage and Theocracy they will get a lot of starting xp points (not to mention you will normally also have barracks early on, to benefit from the Nationhood early bonus and thanks to Aggressive bonus, if you have it).
Disadvantages:
(1) Money shortage - you will have very little money, as the civics are expensive and the strategy does not normally help you generate much commerce. On the other hand, between your high productivity, draft under Nationhood and pop-rush under Slavery, you should be fine as long as you maintain a steady population growth. You will get somewhat better once you discover electricity and start getting commerce bonus for mills.
(2) Not fully available until late game - the workshops and mill tech bonuses, as well as the State Property civic come relatively late in game. This means you will have to wait by building normal mines and farms first, and only later rebuild your infrastructure into mills and workshops.
(3) Civic switching - you may be required to switch your civics around more often with this strategy than with any other (partially because it is a war-mongering strategy and you need a different set of civics for your peace economy and a different set for your war economy).
Best suited for: Warmongers. Pure and simple. Conquest and domination victories are the easiest under this strategy.
I think broadly speaking there are three main strategies of doing so, each of them achieving the best synergies with different game styles, terrain improvements, leader traits and civic choices.
I. Rich Suburbia ("Modern US")
Chief terrain improvement: Cottage
Best traits: Financial (even more commerce), Industrious (wonders mean great people so you are overcoming one of flaws of this system), Expansive (health means bigger cities, so you are overcoming another flaw of there being not enough food)
Civic choices: Universal Suffrage, Free Speech, Emancipation, Free Market, Freedom of Religion.
This strategy relies on building cottages, waiting for them to develop into towns - and raking profits of their commerce.
Advantages:
(1) flexibility (non-Financial civs, with all the above civics and Printing Press tech will be getting +7 additional commerce per town, more if they are Financial; this means extra gold to buy buildings - Universal Suffrage allows that and extra science and culture);
(2) steady progress (you are maxed to gain a steady growth in both science and culture, with a stable increase per turn).
Disadvantages:
(1) not many great people (your food production will be rather low, meaning you won't be able to afford many specialists);
(2) hard to rebuild (if enemy pillages your towns, it will take many turns - half less with Emancipation, but still - to grow it back).
Best suited for: traders and peaceful expansionists (with Freedom of Religion you will give other civics one less reason to hate you). You will be able to found many cities and maintain a relatively large empire, while buying resources from other civs. Diplomatic victory is probably the easiest here (and with the UN under your thumb you will be able to force your liberal tyranny on others mwhahahaha ). Also, possibly the easiest way to achieve "score" victory.
II. Specialist Heaven ("19th Century Germany")
Chief terrain improvement: Farm, supplemented by mines
Best traits: Philosophical (even more great people), Creative (even easier cultural victory, helps keeping people happy), Expansive (bigger cities)
Civic choices: Representation, Free Speech or Bureaucracy, Caste System, Mercantilism, Pacifism
This strategy relies on specialists - and farms to feed them.
Advantages:
(1) lots of great people - you will be having tons of them, especially if you are Philosophical, meaning you will be able to rush buildings, speed-up technologies, run trade missions for extra cash or drop cultural bombs.
(2) small is beautiful - this is the most "build up" strategy - you will be much better off having a few big cities than a lot of small cities; this means less maintenance costs, easier to defend etc.
Disadvantages:
(1) "choppy progress" - unlike the Suburbia tactics, you won't be getting a steady growth here, but rather big leaps whenever you get a great person followed by a relatively stagnant period of waiting for them (compared to the Suburbia strategy at least).
(2) low disposable income - again, unlike Suburbia, your main resource are great people and they are somewhat unpredictable (yes, you can influence the chances of getting different types, but you won't have as much flexibility as Suburbian civ in using them). This means you will also not have much spare cash (unless you run a trade mission with your Great Merchant). And having Mercantilism will hurt your trade income somewhat.
(3) hard to mobilize for war - between pacifism, free speech and not maxed up production, you will have a rather hard time staging a succesful war against someone - sure you will be able to defend well, but only if you hole up in your cities and wait for the enemy to go away.
Best suited for: Cultural perfectionists. You will be able to spread your cultural borders a lot, and even capture foreign cities by cultural flipping alone. Cultural or scientific victory the easiest here.
III. Industrialized State Property ("Soviet Russia")
Chief terrain improvements: Mills, workshops
Best traits: Organized (civic choices are expensive), Spiritual (you will want to change civics often between war and peace economies), Aggressive (in the sense this strategy being useful for a militarist), Industrious (you will zap most wonders).
Civic choices: Police State (for War) or Hereditary Monarchy (for Peace), Nationhood or Vassalage, Serfdom or Slavery, State Property, Organized Religion (for Peace) and Theocracy (for War).
This is a strategy for those for whom peace is just a preparation for war.
Advantages:
(1) High productivity - thanks to state property you get extra food from workshops (normally a production-generating improvement), which normally reduce food - meaning you can build them on many tiles and still maintain enough food to feed your population. And Organized Religion will grant you even more of those precious hammers.
(2) High military power - between free units under Hereditary Monarchy and unit production bonus under Police State you will be able to build many units - and you will want to do so, since in peace they will (under hereditary monarchy) make people happy, and with Vassalage and Theocracy they will get a lot of starting xp points (not to mention you will normally also have barracks early on, to benefit from the Nationhood early bonus and thanks to Aggressive bonus, if you have it).
Disadvantages:
(1) Money shortage - you will have very little money, as the civics are expensive and the strategy does not normally help you generate much commerce. On the other hand, between your high productivity, draft under Nationhood and pop-rush under Slavery, you should be fine as long as you maintain a steady population growth. You will get somewhat better once you discover electricity and start getting commerce bonus for mills.
(2) Not fully available until late game - the workshops and mill tech bonuses, as well as the State Property civic come relatively late in game. This means you will have to wait by building normal mines and farms first, and only later rebuild your infrastructure into mills and workshops.
(3) Civic switching - you may be required to switch your civics around more often with this strategy than with any other (partially because it is a war-mongering strategy and you need a different set of civics for your peace economy and a different set for your war economy).
Best suited for: Warmongers. Pure and simple. Conquest and domination victories are the easiest under this strategy.