Run through Undercroft collecting all gold piles, resource nodes, memory fragments and chests including puzzle chests. Don’t stop to kill enemies as it drastically slows you down and reduces your gold gains per hour, but you can kill some enemies if you can 1 shot and AoE kill them. Do stop to kill purple named enemies as these always drop something useful and if they drop accessories, these can also be sold.
It’s good to note that when fighting enemies you’ll be receiving more damage, since each time you pick up a gold pile you receive a stacking debuff and this can cause you to die more easily on the last boss or the ambush fights.
There will always be events during gold farming runs and you want to skip the long ones, but the ones worth doing include the chained chest events, Loot Goblin, Trickster and Green Cubes. You can do tracer events if you want but the delay on enemies spawning is too long for me.
The time it takes to a run is around 5-6 minutes, even with killing the ambush and last boss. You can skip the last boss if you can’t burn it in a few seconds but you’ll often miss out on extra accessories that can be sold.
From doing this you will earn in the region of 4-6k gold per run.
You’ll also have various level 19 and 20 accessories such as preserved claws, preserving boxes, silver fleece and spoons of good fortune which sell for between 370 to 577 gold along with stacks of Argent Spectre, once you sell all of those the value of each run goes up to anywhere in the region of 6-9k per run!