If you want to buy an item that you need, or you found something that you think could be worth a lot, do not just buy it or sell it to someone right away if you think you are getting a good price. When you do that without checking the market prices you are bound to lose money by either buying something that is overpriced or selling your items way under value. Always check the market, see offers and prices for that item in different places and make sure you are getting the most 2moons dil out of the deal as possible, by either saving 2moons gold when you buy and when you sell.
Depending on what level you are, you may need 2moons gold for a certain item that you need, such as equipment or something else that you want. One way I found to getting a ton of cheap 2moons dil is farming certain monsters that you can easily beat and that drop good items that a lot of people want. The best thing to do is as you go along doing quests note down which quests require certain items that you can find on the market, and when you actually do the quests see how easily you can find those items from monster drops and keep that in mind.