The only other way to pick up coins is to keep an eye on the loot monsters drop when they are killed. Sometimes, if you are lucky enough, you might find bonus chests of green color. They are also loaded with riches. Do not forget to pick them up. Every time you spot a treasure chest while roaming around the world, take the chance and open it up! Keep your coins saved for them. Most of them contain amazing power-ups that build up your playability and restore your stats.