You can use the "Easy gold" glitch to basically get unlimited experience. Once 
you save the life of the Arl of Redcliffe, a soldier of his will appear in your 
party's camp. There will be a box for donating to the army. Enter the screen, 
and select the first option to donate 30 gold. You can do this as many times as 
desired to get a good amount of experience from each donation. If you just keep 
pressing X then Square repeatedly, you will keep quickly donating large sums of 
gold, skipping through the dialog screens, and getting a lot of experience 
quickly. If you start getting low on gold, perform the "Easy gold" glitch again 
with the merchant in your camp. Note: Be careful, as enemies will also level as 
you do. If you get too high of a level and do not have the correct equipment, 
you can be quickly defeated.