Trade isn't about being always in green even if it is a very comfortable situation. Your goal in trading is to keep your economy supplied at minimal cost in cash and supplies.
Types of countries
There are two types of countries in this game, those which are seriously resource-deprived and those who are rich in all kinds of resources.
- The 1st group, buyers, consists of nations that have less than 1.00 resources per IC but also have huge industries to fuel. Japan and Italy are the most prominent members of this group. Germany is on the verge of being one too due to their big needs for all resources except energy.
- The 2nd group, sellers, consists of countries with huge amounts of natural resources, more than their IC can burn, usually coming from their vast colonial empires. USA, UK, USSR, France, Netherlands, Belgium are all in this group of blessed countries which rather than buy resources can focus on selling them.
It's buyer who's responsible for transporting the goods so if you are one and you won't be trading over land (Italy with USSR for example), you should start building up your Convoy fleet right at the beginning (Japan trading with the US for example).
Determining what you need
Before you even start thinking about trading, you should first take a good long look at the resources you already have. See what your stock of them is and how soon you will run out of them. Also see which ones of them you produce in large quantities and which you are really short of.
Make a ranked list of them. Those which you will run out of in very near future (Usually energy) at the top, those you won't need for quite a while very low on the list (usually Rares and Crude). This will give you an image of what you need to purchase and when.
If you have a huge stockpile of something, you should consider burning through it before you make purchases rather than going into green right away and stockpiling even more.
If you have any puppets, they will give you all the resources they produce after they have 1000 of each stockpiled. This means that they sometimes first need to build up such a supply and will start sending convoys to you in a while. So wait a bit and see how much they can provide so you can reduce your purchases by that amount.
Finally check your resource-related research in the Industry tab and see if there's anything you can improve fast in the coming months.
- If you are forced to buy a large quantities of some resource and the tech influencing your research is way behind, the best course of action for you is to research this tech so you don't have to buy as much of that resource in the long run.
- If you have plenty of some resource but lack others, you can consider researching production of your "strong" resource first so you can sell more of it and get money to buy other resources in exchange.
- If you lack all resources, you will have to sell Supplies to raise cash so have your Supply Production tech well ahead of time. Even if you don't need to sell Supplies, it's good to have this tech ahead since it frees a lot of IC to do other tasks.
Picking your supplier
Trade is a long-term enterprise. So you should think well ahead whom you are willing to trade with. If there's a possibility of a conflict between you and your supplier in the near future (Germany buying from the UK) you should rethink your strategy and get another supplier.
In general you should take all those factors into account when choosing your supplier:
- Whether land trade is possible or not (nations on the same continent trade over land without convoys, for example Italy and Germany can buy from USSR over land without using a single convoy ship which could be sunk by the UK).
- Whether you are going to fight this nation in the near future. (if you plan attacking USSR soon, don't rely your whole industry on trading with them)
- Whether your trade routes to this nation will be safe when war breaks out. (for example German convoys trading with the US are easy prey for British fleets)
- Whether this supplier's existence is endangered or not in the longer run. (trading with France, Belgium and the Netherlands is a very risky and short-term thing since they all fall in late 1939 to Germany. So is trading with UK if you are Axis since you will be embargoed as soon as the war starts.)
This means that:
- The best way to go for European Axis players is the historic route of buying all the Rares and Metal from the USSR while Germany supplies all the energy they need.
- The best way for Allies players is to deal with the UK since they can both provide you with virtually all the resources you will ever need and also protect trade lanes against Axis. It's also worth maintaining good relations with the US so they stay closer to the Allies and maybe eventually join your faction.
- Asian and South American countries (Japan, Brazil) are best off trading with the US for the first part of the game (until US at war with them) and then look into a possibility of getting colonies from European powers (India, Malayas, Siberia) or buying from Russians.
If you have plenty of one resource and can sell it for good price to raise cash, it's perfect since it doesn't require you to invest any IC into running your economy.
If you are deprived of pretty much everything though (Japan, Italy), you will need to invest a chunk of your IC into production of Supplies which you will sell to get cash for resources your IC need.
It's easy to notice it means you are investing a part of your IC to have the rest of it running. It means that efficiency of your industry is crucial here. If your Supply Production technology is way behind, you will be forced to invest more IC into Supplies than you would have if this technology was researched ahead of time. So if you are a buyer, you should spend a big deal of time on researching Supplies production.
Another thing worth considering is the fact that when you sell, you get a much better price from countries which dislike you. So selling 50 Supplies to a country with whom you have relation of 0 will net you 1/3 more Money than selling same amount to a country with whom you have relations of 200.
This means you need to make selling deals right away in your game when your relations with other countries is still close to 0 and also try hard to never sell to the supplier of your choice.
- To sell resources, you need to go to the Diplomacy tab and sort countries by the amount cash they earn daily. When you see someone is very rich, you don't have good relations with him and he's out of something you can supply, you should propose a deal for most of his cash right away.
- To sell supplies, you should go to the richest countries on the planet. UK, US, USSR, those who sell large amounts of resources and earn a lot of cash in process. You should approach those you have worse relations with and make enough deals for selling 50 Supplies as you need to raise enough cash for your purchases. Italy usually needs 3-4 such deals (each earning around 9 money), Japan even more, 5-6 usually. Selling to smaller countries is problematic since they run out of cash pretty quickly and the deal dies fast.
- If you are desperate and can't afford producing enough Supplies to pay for your resources you should consider selling a part of your Fuel surplus at a good price. US and France for example are always willing to buy any amount of Fuel you throw at them. Since Fuel is very pricey commodity, it will seriously boost your budget and allow you to stay clear from bankruptcy. Just make sure you sell to a very rich country so they can afford maintaining this deal for a while.
After you are researching more efficient ways of producing your resources and have raised cash for purchases it's time to go shopping. Each deal costs 3 diplomacy points so at this stage it's worth investing more leadership into diplomats to raise those points faster. After majority of deals is done, you can focus on research again since maintaining deals doesn't cost any points.
Building up relations with your supplier
If you picked your main supplier earlier, now it's time to make him your friend. This is easiest done by trading with him for small amounts of goods but making multiple deals. For example, if you are Italy who want USSR to like them you should start by brokering smaller deals for 5x Energy with them one by one until your relations are at 200. It takes around a while to build up your relations so make those deals and wait patiently for month change so game updates it.
Buying and outsmarting the AI
After you have your relations up high, you can make your main deals. Buy what you need in huge quantities per deal (50x Energy, 50x Energy, 50x Energy, 50x Metal, 50x Rares for Italy for example). They will be 1/3 cheaper than if you had 0 relations... so you can buy 30% more resources for the same money just by the simple fact of doing it right!
After you have everything you need, you can cancel early inefficient deals with AI. Be warned though that each cancellation lowers your mutual relations so you will have to build them up again if you run out of something any soon. If you used 5x Energy deals to work on your relations with your supplier, it's usually not worth cancelling them.
Major powers which sell a lot of resources to other countries usually earn an awful lot of cash in process, cash they have little to do with. Those countries should consider buying large quantities of Supplies from friendly nations to free some of the IC invested into supply production to other tasks, producing tanks for example.
One thing worth noting is that most countries (usually minors, but some majors as well, UK or Japan for example) are perfectly fine running out of Crude. A part of your Energy (depending on your amount of IC) is automatically converted to Crude which is converted into Fuel right away.
You don't need stockpiles of Crude, you need stockpiles of Fuel since that's what your tanks, ships and planes use. If you are getting enough Fuel from simple conversion, you shouldn't bother buying Crude but rather let your country run out of it and only purchase the amounts you can both afford and convert right away.
In the long run you want to annex or puppet a country rich in Crude to boost your Fuel production with spending money on it. You can find a lot of Crude in Romania, Venezuela, Iraq, Persia and in the Dutch and British colonies in the Malayas (Borneo, Aceh). What's best, when you annex a country which was rich in Crude, you take over their supplies as well so you can get even a few thousand of unsold Crude during your conquest.
So if you are a major conqueror (Japan, Germany, Italy), you should prioritize conquest of countries rich in Crude rather than build a stockpile of it with trade.
Trade as a tool of diplomacy
If you are in a faction, nations with whom you have good relations are naturally drifting towards your faction. Trading with someone gives you +15 relations per deal so you can (and should) your trade as a tool of influence to draw more nations towards your faction rather than spend Leadership and diplomacy points on the same task.
On the final note, it's good to describe the way AI trades resources:
- AIs always first burn through reserves first and only then start asking around to purchase what they need.
- AIs often try to build up relations with other countries using smaller supply deals. So if you get a proposal to sell 0.39 supplies somewhere, it's not meant as a serious business deal but rather as a way of building up relations.
- If you are a seller and want AIs to buy your extra resources, you have to be aggressive about it checking very often which AIs have Money surplus and offering them deals even if it says impossible.
- AIs often run out of cash. They run out of it on one day to move their Consumer Goods slider on the next day to produce surplus cash and purchase from you. So very often you will be selling to AI not every day but every 2nd day. On the day they are short of cash and can't pay for the deal they sometimes ask for another deal for same amount of goods, you should treat it as a bug and refuse it. For example, UK player will be offered many deals for 12 Rares with Poland while the first deal for that amount goes dead due to Poland not having enough money. This should be refused since refusal unlike later cancellation doesn't cost any relations.
- Some AIs just can't afford trade and will be bankrupt constantly. If you notice some AI can't make their ends meet and has multiple dead deals with you, you should refuse any further deals they propose and don't offer them anything. Spain is a good example of such a country.
- Crude exporters, even small ones like Venezuela or Romania are extremely rich for their size so your exports should focus on those countries since they always have money to pay for it.