To add onto Gen Fire Dragon's, not a separate solution.
I have found the best ways to rack up the studs (even if you do or don't have the multipliers, I don't have them, but have access to get both the 8x and 2x multipliers, just need the right amount of Studs), is to get the Studs in the Hub and the Levels using Marty (you usually acquire him early on in the game), he is the one with the White Face, Brown Shirt, and carries the Blunderbuss.
I use Marty because of the Blunderbuss, as he has the ability to break through the silver objects, this is easily visible in the very first room in he first level, at the end of the room, there are silver gates, which you can break through to get an extra ton of studs (even a purple one, several blue ones, and lots of gold and silver ones), and some grates over to the left which connect together through an underwater path, that once again contains several ones (just discovered this path Yesterday actually).
Once again, this is not an actual solution, it is just an add-on to Gen Fire Dragon's solution.
Here is a link for his profile on Brickipedia in case you have issues finding / acquiring him in the game...:
http://lego.wikia.com/wiki/Marty.
Another achievement that can be obtained while getting this achievement is There's the Jack I know, which is to get True Pirate in all levels: