Belfran said:
I know, I know: Civ games aren't War games. They
can be, though... right?
I've started winning games (by time victory *eeeewww*

), Space Race and by Diplomacy. I am a Warmonger at heart, so I want to try a win by Conquest and I need some advice!
I'm pretty much a warmonger so I hope I can help. You haven't said anything about the game setings you use most of the time, so my advice is coming from the perspective of playing Terra or Continents maps on Prince as any of the aggressive leaders (most often Napoleon), with all other options being defaults.
Belfran said:
I usually go for the first religion available (generally Hinduism) and stick with that for all the game. I beeline to military oriented techs and start to build armies! I switch to Civs that help me maintain happines in war, and get unit upgrades. So far so good, right? Wrong. Trying to plan ahead, I also try to build a strong economy to maintain my wars....whilst doing that I go and build some wonders for border expansion to reach resources needed for my armies. So I start to spread out too thin in research and construction and ages fly by me! I then start to go after mine enemies (neighbors if hostile, friend's neighbors if otherwise) and while I do manage to extinguish two or three civs, I can never see the end of the game squashing everybody out!!
Skip the starting religion all together. Your neighbors will do this for you. Even if you end up being alone on an island on a continents map, you will be able to get along just fine with no religion at all. Taking a holy city is every bit as good as making one yourself, and requires zero research. The _only_ way it works out better for you is if you found two religions in the same city so you can get 200% bonus on two shrines worth of income. It isn't worth it.
If your chosen leader starts with mining, then research bronze working and kick out a worker right away to do forrest chops. If not, research mining and build a warrior in the interim. Once the worker is out, start choping down trees and useing them to build warriors. Every tree in your city radius dies, and plenty outside it too. After your first two to four warriors kick out a settler, then back to warriors. These warriors all need to be out scouting for other civs. You don't even need to leave one at home in the opening turns, human barbarians won't appear for awhile and I've never once had the computer initate a war this early.
Don't let them auto explore, control them manualy it will be much more effective. If you find annother civ's city radius, make sure to walk the entire edge of it and see what territory he has. If you spot a worker inside the radius, go ahead and start a war right then and take the worker. If you see a hill/forrest, start the war right then and fortify your warrior in it. The AI will basicly be shut down trying to uproot you and he has essentialy no hope of doing so. If you started a war over a worker and there are no hill/forrests in his radius, find one between his city and yours and take up residence there until he can be sued for peace. If you did find defensible land, then get a second warrior over there for backup as soon as reasonable.
Focus research toward iron working. You wont have it by the time your first settler is founding a city, but you should by the time your second settler is ready. Every single game I've found iron somewhere on the map exposed by all those scouting warriors. Start building a road to it the moment it is exposed to you, and get that second settler over to found a city by it.
The first expansion you built should make a barracks, unless you started with Mysticism. If you did, then stonehenge and chop it down. After iron working is researched, but before your third city is built, often there is a window to research mysticism and get stonehenge built in the second city (after the barracks for non mysticism leader).
Long before your iron city is built, you should get a promotion or two from the warrior pair holding down an AI player. Medic promotions first, will drasticly cut recovery time and guarentee you don't lose the pair. Long as you dont lose your toe hold, the AI is going to have a hell of a time going offensive.
Once that second settler is sent out, capitol switches to barracks. Both/All workers will need to complete that road network as fast as possible, and idealy all three cities will be hooked to the iron before capitol and third city are done with barracks. Second city will be on stonehenge usualy for a good 15 turns, but get it up to speed as well.
Research post iron working should be hunting->archery, and then pottery->writing->math->currency. Archers will take 10 turns tops, needed to actualy start defending your land from barbarians. If you see a barb, move an archer out to a hill near the barb, they will always suicide on you. Currency is required if you actualy want to keep up the conquest. You are quickly going to be reduced below 100% science, and you will need markets to slow the decay. After currency, go for construction. By the time you research this far, your war machine will be halted without catapults.
With barracks and iron, kick out swordsmen with city raider. If you didn't get iron, copper will get you axemen with city raider. Both are plenty good. Build as fast as you can and ship them to that fortified point being held by a warrior. Steamroll the AI at 1:1 odds. 3 defenders will fall to 3 swords this early in the game, they have no chance of stoping your swords with pathetic 20/40% defense boosts and base strength 3 from archers.
Almost never will the first AI steamrolled this way have more than 1 city. Hes out of the game now and you have a very nice city. Leave a warrior on guard duty and move out with your swords/medicwar for the next target you spotted. New aquisition builds barracks while your workers build a road to it. Typicaly I make this city pump out nothing but archers, to move in behind the main army and secure conquests and to spread out in a picket on hills to prevent barbarian spawn.
If one of your targets has a couple of cities, burn down everything except the capitol unless it is in a very nice location. You cant actualy afford to support a large empire yet untill you can get markets and some cottages up in a few of your cities. Dont be afraid of even 40% science. Your empire should be FAR larger than anybody else by the time it gets that bad, and as long as you aren't picking up poorly located cities you will still be able to stay reasonably close to the computer even with his resarch advantages and your low science rate. Knowledge of Music won't save his ass when level 4 city raider 3 swords with catapult back up come a knockin'.
The only things that should hault your rightous rampage are science droping below 30% or running out of targets. It is not unusual to exterminate three opponents during this initial round. By the time it ends, you should have catapults and currency. Your new research targets should be metal casting and code of laws, and a little bit of concern for backfilling technologies such as... fishing, animal husbandry, agriculture. you know, the basics your barbaric little civ has been ignoring in favor of bloodlust.
This lull is the first consolidation phase. At this time, you focus on generating commerce in your cities. Build markets in most cities (you will never be 100% science all game, so it will benifit you in all but the worst towns) and build courthouses when that becomes available. Cities near the capitol build markets first, your farthest conquests build courthouses first. During your spree odds are very good that you have picked up a holy city (or two!). Now is a decent time to go ahead and make one of those your state religion. If once of the holy cities has a shine already built (not uncommon), then make that one your state and dedicate a city to manufacture of missionaries to spread it out. 1.25 gold from every city goes a long way to paying for the empire. During this time, also identify cities with plenty of flat land for cottages. You need to start specializing a few cities for wealth to pay for the next expansion phase.
If you have more neighbors left, then the first consolidation phase is over when your science rate can get back to 60%. If you have exterminated everybody on your island, then the first consolidation phase isn't over untill you have researched astronomy and found yourself some new friends. Typicaly you will now have macemen, drop the science down a notch or two and get all your city raider 3 swords upgraded asap.
Second expansion phase goes very much like the first, and typicaly ends when the enemy is fielding rifles before you. Third expansion phase will be as soon as you can upgrade all those city raider 3 maces to rifles and it usualy lasts till the game is over. By that point your empire will be monsterously large, and you will be able to exert overwhelming force with only half your cities focused on the war effort. With the other half of your cities able to support other endevors, funding the empire should be trivial.
Note the total lack of diplomacy. If you intend to go with a domination win not a conquest win, then pick a civ as far away from you as possible to be friendly with. Open boarder agreements are fine if anybody will sign for them, extra trade doesn't hurt. However, you don't need to toady up to anybody. You have the millitary might, you have an overwhelming tactical advantage because the computer players are stupid, and you are planing to kill them all eventualy anyway. If it is a minor threat then sure, caving in won't realy hurt. But never give up any technology. They will already be ahead of you anyway, don't help them backfill.