My tip is a simple one , i haven't yet got the time to put in some good hours in gold making so when i have time i got to the ah and look at the darkmoon cards prices .
For example all the War cards on my server cost 18500 g , the trinket on ah is 30.000 g . If you want to sell fast like me in chat i offer it for 24-25 k gold , and i only buy the cards when the guys agrees to buy it from me . Sold 5 trinkets in 30 min just from this .
Olso be sure to check the Joker card prices since sometimes they are cheaper than some Darkmoon cards , so you can trade it when the faire is in town and sell it on ah .