I thought I'd share my method of building cost-efficient chiefs and a high rate of success for conquering, for all those who are interested. This may not be the best way for everyone but it works very well for my style of play.
I only play on x3 or higher servers, but I see no reason why this won't work on a normal server as well.
Gold is not required. Travian PLUS is recommended for convenience. Insta-build is NOT necessary at all on a very active account. I only listed the prices for Teuton settlers/chiefs, adjust accordingly if you are a different tribe.
First off, here are the total cost in resources for the important buildings starting from level 0, rounded up or down to the nearest thousand...
Level 10 Residence: 60,000 total resources
Level 20 Residence: 775,000 total resources
Level 10 Palace: 91,000 total resources
Level 15 Palace: 332,000 total resources
Level 20 Palace: 1,200,000 total resources
Level 20 Academy: 252,000 total resources
3 Teuton Settlers: 75,000 total resources
Research Cost for Teuton Chief: 69,000 total resources
Building Cost for Teuton Chief: 115,000 total resources
In my eyes, the value of all resources are much higher the first half of a server compared to the 2nd half... you really want to make wise spending decisions and cut down on wasted resources as much as possible early game or you slow down your progress. As you can see from my numbers above, there is a huge price difference between a level 10 and level 20 residence.
Here I will show what I feel is the most cost-efficient way to build a strong foundation for mass amounts of chiefings.
Expansion slots are important and the difference of conquering capabilities between an account with good or bad expansion slot management is pretty significant. If you plan on conquering more than just a couple inactives, you really need your army village(s) to keep all it's expansion slots empty, once you are ready.
The first few villages I build a lvl 10 residence and settle from there just like normal. My typical order is: Spawn Village --> best close 15c for future capital --> army village (either main or 2nd army, depending on the distance from your spawn to your 15c) --> feeder village --> another feeder village.
Once I have at least 4-5 villages and good resource production, I start creating new villages WITHOUT using any expansion slots. This part takes a bit of a investment in time and resources but it really pays off in the future.
Creating New Villages Without Using Expansion Slots.
1) Save up enough CP for 2 new villages and have 3 settlers ready to go. (We will call this Village X)
2) From Village X, settle a new village (We will call this Village Y)
3) In Village Y, ONLY build a Main Building 5, Rally Point 1, Residence 10, and a Warehouse/Granary 8. (Level 8 is the lowest you can go to hold enough resources to build a Teuton Settler)
4) From Village Y, settle a new village (We will call this Village Z)
5) Destroy Village Y and keep Village Z.
Now you will have created a new village without using any expansion slots at all. It only cost about 150k in total resources. Keep repeating this process for all the new villages you create, until you stop settling and start conquering.
Freeing Up Used Expansion Slots For Army Villages.
Now that you have plenty of villages that have no used expansion slots, it's time to free up the used expansion slot for your army villages so they can have more chiefs. This is important because it will make future conquering so much easier and prevents long drawn-out chiefing attempts that can go bad quickly.
In one of these villages you created, build a level 15 palace (cheapest building for 2 chiefs by far), level 20 academy, and build 2 chiefs. Use these 2 chiefs and about 50 escort troops to conquer whatever village is taking up a expansion slot for your main army and secondary army villages. You should not have any troops built in those 2 villages that you can't afford to lose! Don't waste resources building a wall in those 2 villages either, unless you get attacks worth defending. The goal is to end up having 0 used expansion slots in your army villages.
Once you have 2 army villages with 0 used expansion slots, tear down that palace and change capitals if needed. You should build chiefing infrastructure in all your villages with 0 used expansion slots... don't over extend your spending just to rush this, it's not needed. Get the academy to 20, rally point to 5, and you will need a level 15 warehouse/granary to have enough storage to build a chief. You will need a higher warehouse to reach a level 20 residence but for now, a bunch of level 10 residences with just 1 chief will do the trick. A level 15 palace is half the price of a level 20 residence... you can build 2 chiefs in 1 village at a time with a palace if you want but it is risky as any mistake that kills a chief after the palace means you will need to build a level 20 residence to rebuild that lost chief.
I like to build a level 20 Residence in my main army village and a level 20 Palace in the secondary army village. You can switch these if you like but I have found that it's much easier to lose a chief in the clear if it has 3 chiefs vs. only 2. Being able to conquer with only 2 attacks total cuts down on the chances your target will go to DEFCON 4 to defend. You must have at least a level 10 TownHall in both these villages! Once you conquer a village with these 5 chiefs, only using a single attack from each, you will later re-conquer your new village from any of your other villages, when it is safe for you. This way you can rebuild the lost chief in your army village to rinse and repeat.
The idea behind this strategy is to use as few attacking villages as possible, lower your chances of being stopped by sending out several fakes that look exactly the same as the real attacks, and use the element of surprise to your advantage. Don't forget to run large parties, aim the cats at the correct building, and to be online when the attacks land so your 2nd army does not starve. And use a proper amount of rams! Sending sloppy fake attacks opens the door for failure.
At this point, you should have at least 2 army villages, each with a level 10 Town Hall, 1 with 3 chiefs, the other with 2 chiefs, and several other villages with at least 1 chief. You are now ready to hit the start button on a kick-*** machine!
First you need to figure out how many chiefs it will take to conquer a village from another account and plan accordingly.
Make sure to enter the correct total ACCOUNT population numbers for you and your target, it is a big factor in how many chiefs it will take.
If your target has even or higher population than you, it will take a max of 5 chiefs to conquer, if both sides are running a large party.
If your target has lower population than you, you will only be able to conquer with just 5 chiefs if you are running a large party and they are not. If you have higher pop, you need to make a judgement call to guess if your targets village would have a lvl 10 TownHall AND a large party.
Next you need to write down travel times so you can figure out the order you will need to send real and fake attacks.
I write down the travel times by cats/rams from my attacking villages to my targets capital, the village I want to conquer, and 2-5 other high value villages that look worth defending. Depending on the distances between all these villages, you may want to send your secondary attacks at cat or ram speed. Opening up new tabs on my browser for all this really speeds things up.
Personally, I like to have all my real/fake attacks land at the same second, or within 5-10 minutes if everything is too close... it puts extra pressure on the target to make a mistake or simply lose all hope. So after I have my travel times written down, I create a time line so I don't get confused or mixed up halfway through. I start from the longest travel time and note how much time in between the next attack, list where the attacks are coming from and going to, if it's their capital so I send multiple waves, and if they are real or fakes. I make sure to give myself enough time to put extra focus and attention on launching the real attacks without any mistakes. Once I begin sending attacks, I write down the important landing times that have already been launched.
I feel it's best to keep the element of surprise. Don't show your fangs unless you are ready to bite! For a quality active account, it's best for your first real attack against them to be a successful conquering attempt. If you are planning on chiefing something like another persons army village that is a serious threat, do not make it obvious by sending scouts checking the buildings... just send without warning and put the cats on a doubleshot aimed at both the residence and palace. The goal in a situation like that is to make their troops disappear, not preserve all the buildings. If all your attacks look like fakes and you have shown no pattern of aggression, there is a chance your target might not feel threatened.
Once you successfully conquer a village with this strategy, re-chief that village later from another village of yours to free up the expansion slot in your army village, as long as you have enough CP to settle a new village.
Using this strategy, you will conquer on the first try if done properly, you won't be "that guy" who is struggling for hours or days just to take 1 village. You will save a lot of resources early when they matter most. You will have plenty of chiefs always ready to take any village you want, when you want it, or to help your allies if they are lacking chiefs.
This may not be the best strategy for everyone but it works for me and I've have amazing results doing this. Good luck.