Quickest way is to buy platinum and sell chests to other people.
The other option is to farm mobs. Level up and as you level you'll get items to sell to the vendor. Sell to the class skill book vendor in Farcrag. They give the best price for vendor trash. But this is a slow way to get cash.
Right now cooking is hot. You can run around and pick crops out of the field, and sell them to people. Not sure of the price people would buy them for, but it's an option.
The other quick way to get cash is to watch the auction house and look for a good deal. Then resell that item for more gold than you bought it for. Buy low, sell high
I don not recommend dicing. People claim to get lots of gold from it, but it's also a great way to get scammed.
Also, join a good clan on your server. Many clans resell items for good prices within the clan. join your clan's buy/sell channel in social media (Band, Discord, Facebook, etc.). You will hopefully find a good price for the item you want to buy.