War is often overlooked as being profitable in this game, food / weapon costs are often the prohibitive factor, and all but those with the most real-life disposable income or strength will struggle to earn an income from the battle hero achievement.
However there is one achievement which is both easy to earn and highly profitable. That my friends is the Freedom Fighter medal.
How much gold can I make?
This varies greatly depending on your country's market and the speed you wish to progress, however I have created an online spreadsheet that you can use to determine for yourself. Try it out here: Freedom Fighter profitability calculator
Here is my output:
The requirements increase for each medal you earn and reset on every 25th iteration, however the requirements increase slowly and remain profitable throughout with the current gold price (roughly 203cc).
The calculator assumes that you will always have to move to fight in a resistance war and doesn't take into account the rewards you will receive from the weekly battle page challenge which often include moving tickets, .etc, so likely understates the amount of profit.
Maximizing weapon expenditure.
First and foremost, we are buying weapons to kill faster and use less energy, not to do more damage. So the ideal weapon is the one that will kill the enemy in the least number of hits for the least amount spent.
For most of us we do not want to do this calculation ourselves, however the greasemonkey extension eRepublik Stuff++ script will do this for us (Firefox or Chrome required)
Figure 1 - eRepublik Stuff++ overlays the hits required for each weapon to kill the current enemy.
Not only does it show us how many hits are required but it also calculates the cost per hit of each weapon type on the market page. Often a Q2 weapon will cost less per hit than a Q1.
Figure 2 - eRepublik Stuff++ overlays the cost per use of each weapon on the market page.
With this knowledge you can stockpile the cheapest cost per hit weapon. Do not stockpile weapons in single quality increments! As in, do not purchase Q1 and Q2 weapon types but purchase Q1 and Q3 instead. This is because weapons of similar quality often equate to the same hits per kill.
Likewise if there is a large gap between the cost per hit of a weapon and the next highest then do not purchase above this quality, we are trying to find a balance between cost and energy expenditure, buying Q7 weapons will rapidly decrease the profitability of this method.
As you battle, switch to the cheapest weapon you own that will kill the enemy in the least number of hits.
Use moving tickets.
I can't stress this enough. If your market permits it, use a moving ticket. Currently a Q3 ticket in Indonesia sells for roughly 34cc, compare that to the 60cc I would spend otherwise and the choice is obvious.
Picking a winning resistance war.
This is easy. There is a very useful online tool for finding all the current resistance wars and their chance of success based upon current performance: http://ereptools.info/battles/freedom
Figure 3 - screenshot of http://ereptools.info Freedom Fighter calculator.
If you want to do this manually, make sure to only enter a resistance war once the resistance has a clear influence lead and the war is nearly won ( > 50 battle points to the resistance), e.g., If the resistance has 55 points and the defender 10 points then it is safe to assume the resistance will likely win, you can also check who holds domination in the current wars. As division 4 earns the most points it is often useful to check that the division 4 battle is swayed in our favour.
Don't forget the mercenary.
There is another 5 gold achievement up for grabs when you kill 25 enemies for 50 different countries. It's certainly not profitable to seek exclusively however you are likely to meet most of the requirements as you move around and fight in different resistance wars. Consider it a bonus.
That's all folks!
So in conclusion, forget making companies, wasting your time buying and selling products on the market for marginal increases. Go fight, win rewards and make more gold than ever before.