Tell me more about social policies, please.
Civ V features 10 social policy tracks. Here's a breakdown of how the system works.
Every city will generate a number of culture points per turn. Culture points have a dual purpose. The first and primary purpose is to fuel the acquisition of social policies. The second purpose is to foster natural expansion of your territory by acquiring tiles.
The amount of culture points necessary to get a social policy goes up as you acquire new social policies. The culture point cost also goes up as acquire more cities (each additional city increases the cost by a certain percent and I'm not sure if this percent varies). So if your first social policy unlocks tradition for 10 culture points, your second social policy can unlock a second social policy or get one of the first tier social policies in the Tradition tree. Social policies provide passive benefits to your civilization. For instance, unlocking Liberty cuts the training time of your settlers in half. Generally, each track is focused towards providing a benefit in an area. Additionally, each social track requires you to be in a certain age to acquire. You start out with access to just Tradition, Liberty, and Honor.
Tradition: Excellent for small city count civilizations. It provides a lot of boosts to your capital city and some territory benefits in order to allow you to better compete with larger civilizations.
Liberty: Excellent for high city count civilizations. Some of the bonuses are good regardless (+1 culture per city, +1 production per city) but the others really shine with more cities.
Honor: Excellent for military focused civilizations. Provides a lot of boosts that increase combat effectiveness or ancillary effects related to soldiers.
Piety: Perfect complement to small civilizations focusing on culture. One of the final social policies grants free social policies.
Patronage: Perfect complement to civilizations seeking a diplomatic victory. Provides a lot of benefits related to city-states.
Commerce: Provides you money or saves you money. It's not geared towards any specific victory type, but all of its social policies are useful.
Freedom: Another perfect complement to a cultural victory. This has two major boons to culture. The first is doubling culture production in any city that has a world wonder. The second is to halve the cultural point cost of all future social policies.
Rationalism: The science track. Everything about it is related to science or because of science producing buildings. Universities give happiness, a happy society increases science rate. In addition, you can get 2 free technologies from the social track as well.
Order: This appears to be a track geared towards expansive civilizations. It has a policy that decreases unhappiness from the number of cities you have. It increase your production rate as well gives bonuses to your units while in your territory.
Autocracy: This is the mack daddy of military policies. Decreased cost for purchasing your units (33% from this and 25% from Commerce). You reduce the unhappiness from annexed cities (though you could always raze or make them a puppet). Causes your damaged units to have +25% damage. Doubles your strategic resource output (necessary for the better units). Finally, there's the one policy you activate just prior to going to war with a major enemy. For 20 turns you get a 33% bonus to your combat strength. These are huge bonuses, but they come at a cost that I explain below.
You can pick and choose from policies as you see fit with two exceptions. The first exception is that you must have acquired all the prerequisite social policies in previous tiers for a track in order to access latter tiers. The second exception is with the Liberty, Freedom, and Autocracy tracks along with the Piety and Rationalism tracks. If you take Autocracy, you cannot take Liberty or Freedom without giving up all the social policies you've earned in Autocracy. The same exists for Piety and Rationalism.
The easiest path to a social victory is using India and going the Bollywood method. The Bollywood method is to obtain the cultural victory with only 3 cities. India is perfect for this because the unhappiness you gain from population is halved, while the unhappiness you get from cities is doubled. When I did this method I was earning my 19th and higher social policies at a rate of about one every 10 to 12 turns.