This will come naturally, I am sure. HOWEVER
If you need this done quickly, and you are in favor of farming, and you wouldn't mind a
pile of gold .... please read on.
This method will allow you to get this quickly, and soon after you get access to the war table.
1st step
You need to have access to the mission where you collect gold. (It is on the left side of the Fereldan side (the right card)) .
Save before you enter the war room.
Close the game.
Go into settings and disconnect from the internet. (go offline)
Hard power down your console (hold on the light on the console until it powers down)
Turn on the console again.
Go into settings and change the year to: 1916 (assuming you are in 2015)
Load the game and continue.
Enter the war room.
Select on the GOLD money mission - choose the character.
IT SHOULD AUTO COMPLETE GIVING YOU THE MONEY AND COMPLETING A MISSION.Do this a whole bunch more times. You will have to count yourself since the acheivements cannot be tracked while you are offline.
When you are satisfied, close the game down (don't just minimize it - close it) and go into setting and go online again. Then you load up the game if you have done the 50 missions the achievement will pop around the title screen.
NOTES/CAUTIONS!!!!!!For me when I was doing this, the QUEST WORLD MAP was a bit screwy and the cursor would have a hard time going where I wanted it to go. When I went back online, the problem was fixed.
If you use a turbo controller (as I tried), the game will crash. At least it did for me.
I would recommend you exit the war room every so often to make sure you save.
You can also use this solution for:
Since you can get unlimited gold.